The Internet Corporation for Assigned Names and Numbers ( ICANN ) is a private non-profit organization of U.S. law, established in California City Marina del Rey .

Task

ICANN decides on the basis of the management of top-level domains , and thus ICANN coordinates the technical aspects of the Internet, but without the right to set binding. ICANN was under 30 September 2009 the Department of Commerce (Department of Commerce) of the United States and thus the U.S. government . Since October 1, 2009 and replaces a joint “declaration of binding agreements” (Affirmation of commitment) the previous agreement (Joint Project Agreement, JPA), which representatives of governments and interested stakeholders should regularly assess whether the ICANN organization to fulfill its responsibilities in accordance with statutory .

ICANN is sometimes used as a sort of world government of the Internet means. The governments of the world are in the Governmental Advisory Committee ( Governmental Advisory Committee , GAC) represented the independent seat at the EU Commission in Brussels has one. As the headquarters of the organization even after 1 2009 in the U.S. remains October, network management organization is subject to the continuing American jurisprudence.

Formation

ICANN was in October 1998 a coalition of various interest groups (business, technology, science and users) founded by. Legally, it is in ICANN is a private foundation based in Marina del Rey, California. The ICANN is responsible for a number of technical requirements, previously of the IANA and various other groups were taken, focusing on.

Objects of the work of ICANN

In order for the Internet, certain names and addresses are globally unique. Therefore, ICANN coordinates:

• on the Address Supporting Organization and the Country Code Names Supporting Organization (ccNSO), the Internet domain name ( domain name system , especially the DNS root name server )
• the IP addresses ,
• in cooperation with the IETF protocol parameters and port addresses of the Internet protocol suite .

Organization

The Board of Directors of ICANN is composed of 21 members from around the world. 15 members have voting rights: to be a night Nominierungskommittee elected, two by the Address Supporting Organization (ASO), two of the country-code Name Supporting Organization (ccNSO) and two of the Generic Name Supporting Organization (GNSO), which coincides CEO . Six non-voting members are nominated by advisory organizations. 2000 members, five representing the user base of a continent selected public, with the expiration of their time member of the 2003 public election, however, abolished.

Chairman of the board is Peter Dengate Thrush. President & CEO of ICANN since 2009 July is Rod Beckstrom, chief operating officer since September 2010 Akram Atallah. Board members were from Germany until 2003 Helmut Schink ( Siemens AG ) and the journalist Andy Mueller-Maguhn (Deputy Chairman of the Chaos Computer Club Berlin e. V.), the representative was elected as European. Another member from Germany until 2006 Hultzsch Hagen (a former board member of the German Telekom AG ). Karl Auerbach , the public representatives of the North American user base 2000 to 2003, sat down for more openness and transparency of ICANN for a. In 2002, he complained before a Superior Court in California successfully for access to the books.

Alternative root server

An alternative to the ICANN root servers to the OpenNIC Project is . To 31 December 2008 formed the Open Root Server Network (Ørsnes), which partially IPv6 was enabled, an alternative to the ICANN root servers

The Internet Assigned Numbers Authority ( IANA ) is an organization that the allocation of IP addresses , top-level domains and IP protocol numbers and the allocation of port controls. The forerunner of the IANA originally consisted of only one employee, Jon Postel .

IANA delegates the local registration of IP addresses to Regional Internet Registries (RIRs). Each RIR is a specific part of the world for, specifically:

• ARIN for North America
• RIPE for Europe
• APNIC for Asia and the Pacific region
• LACNIC for Latin America and the Caribbean
• AfriNIC for Africa

The IANA distributed IPv4 addresses in large blocks (typically / 8 in CIDR notation) to the RIRs , which will then by their own rules for the allocation of addresses to end customers (in this sense, providers or organizations, their IP addresses themselves manage distributed), in which case most / 19er-or / 20 blocks are allocated.

The IANA is also responsible for delegation and allocation of IPv6 addresses in charge, it has been easy here, but insofar as they contain large blocks to the RIRs and distributed very near future so that other delegations have made ​​unnecessary time on easy. The stock of delegated IPv6 addresses currently exceeds by several times the demand, since IPv6 slowly into production is the first place.

The IANA is organizationally a division of ICANN and is thus at least indirectly under the influence of the U.S. Department of Commerce .

The relationship between ICANN, the ccTLDs and RIRs can be seen as, at best, highly political, “described to be”, and since ICANN again tried again, the IANA to the registries to exert influence over, there were now several proposals to complete by ICANN to decouple IANA whether with or without the cooperation of the U.S. government.

The host name (including site name ) is the unique name of a computer in a network . It is predominantly the electronic data exchange (eg e-mail , Usenet , FTP ) is used to communication partners in a human-readable and noticeable specify the format. The reaction of the host name to a machine-readable address is on the web today, mainly via the Domain Name System (DNS) , historically the file / etc / hosts . In local networks, the reaction is carried out by some DNA , some still with NIS and other proprietary protocols. What names are technically allowed, governs in the case in the protocol used for name resolution – on the Internet so the Domain Name System .

Hostname as the name of a physical system

The host name of a physical system ( computers , host ) is the name under which the system itself knows and with which the system reports. Visible host name can be that when a computer system sends an email such as sender of status messages or bounce messages or if a user on a server logs. The host name can be UNIX-like systems with the command hostname and set to be read.

For computers that are directly on the Internet are available, is usually a Fully Qualified Domain Name (FQDN) hostname is used as, For computers, the only one LAN are reachable, is part of the domain part is omitted and only the local part is used (in this case mail ), as the domain of clear distinction in this case is not necessary to is.

The local part of the hostname of physical systems is often based on characters from literature and film (especially SciFi Comics), mythical beings or gods, or selected and depends on the intended use of the computer (eg, ns, mail, ftp, serv1, serv2, SERV3 etc.).

Hostname as the name of a network node

In the Domain Name System are AAAA Resource Records and A resource records entered, the name an IP address assigned. This name may or may not be the hostname, the host with that IP address out of. This may be possible that a host is reachable under different names.

Example:

On a host running a Web server serves multiple customers of the. The site is one of about beispiel1.de, that of the other accessible via beispiel2.de. Both names are from the same IP address in the Domain Name System database.

The full name of a network node is usually composed of a part that describes a service (such as www, mail, ftp, etc.) and a domain part. This practice, however, evolved over time, and makes sense only in case if these services are different from hosts provided. for the Domain Name System is no difference between domains and subdomains Since there is, can A resource records directly to the domain of entry.

Guidelines

Host Names are as all domain names from several “labels” which are separated by one point to each other. Each label must be 1-63 characters long, up to the domain name must include a total of 255 characters.

Unlike domain names, only hostnames in the ASCII characters AZ (upper and lower case does not matter), 0-9 and the hyphen - exist. The individual labels may not start or stop a hyphen. Other than the special characters dash (and the point between the labels) are not permitted, although they are still used occasionally. Underscores are often on Windows systems used, although according to RFC 952 are not allowed. Some systems, such as DomainKeys and the SRV resource record , use the underscore deliberately to ensure that their particular domains with host names not be mistaken. Because some systems check the validity of hostnames only problem is the use of invalid characters like the underscore out to various systems in the world are connected with the.

The host name de.wikipedia.org therefore consists of the DNS label de , wikipedia and org . Labels such as 2600 and 3Com may be used in hostnames, -hi, and hi * * are not valid, however.

History

• 20. September 1971

RFC 226 – Standardization of host mnemonics

6 characters to describe a host name, in the example are all uppercase letters and numbers used

• 22. September 1971

RFC 229 – Standard host names

8 characters for the description of a host name, in the example are all uppercase letters, numbers and hyphens used

• 5. October 1971

RFC 237 – NIC view of standard host names

At least 8 characters with regard to the use of up to 12 characters in the NIC

• 17. November 1971

RFC 280 – A Draft of Host Names

A first-draft list of hosts with hostname in the network

Be used up to 11 characters

• 21. December 1971

RFC 289 – What we hope is an official list of host names

The first official survey of hosts with hostname in the network

Be used up to 11 characters

• 12. December 1973

RFC 597 – Host status

An overview of hosts with hostname in the network

Be used up to 12 characters

• 10. January 1974

RFC 608 – Host names on-line

48 characters to describe a host name, consisting of capital letters, numbers and the hyphen

• 1. March 1982

RFC 810 – DoD Internet host table specification

24 characters to describe a host name, consisting of capital letters, numbers, the dash and a point

• October 1985

RFC 952 – DoD Internet host table specification

The point may only be used to separate each domain name

• October 1989

RFC 1123 – Requirements for Internet Hosts – Application and Support

Software for resolving host names must support up to 63 characters and should support up to 255 characters

A Fully-Qualified Host Name (short FQHN,) is a host name , either as a fully qualified name of a domain ( Fully Qualified Domain Name , FQDN is shown) or a numeric IP address of a computer. ^{[1 ]} The FQHN denotes a particular computer unique.

Is there such as a company with the domain “example.com” a subnet “administrative” and is in this one computer with the host name wks1 “then a FQHN the FQDN of this host” wks1.administration.example.com. . Another FQHN is the IP address of the computer, for example, ” 192.0.2.123 “.

The term FQHN is including in the two RFCs 1153 ( Digest Message Format 1990) and 2109 ( HTTP State Management Mechanism 1997) used. RFC 2109 has now been through the RFC 2965 ( HTTP State Management Mechanism 2000) replaced by, in the longer term appears not.

A name server is a server , the name resolution offers. Name resolution is the process that allows names of hosts or services in a computer-editable address dissolve

Most name servers are part of the Domain Name System , which is also in the Internet is used.

Name servers are programs on the one hand to answer questions about the domain name space, in the language are, however, the computers that run these programs, referred to as name servers. A distinction between authoritative and non-authoritative name servers.

An authoritative name server is responsible for a zone. His information about this area, therefore, are protected considered. Each zone is at least one authoritative server which primary name server. This is the SOA resource record of a zone file listed. For redundancy and load balancing reasons, authoritative name servers are almost always as a server – Cluster realized, the zone data on one or more secondary name servers are identical. The synchronization between primary and secondary name servers is via zone transfer .

A non-authoritative name server gets its information about a zone from other name servers as it were from second or third hand. His information is as secure not considered. Because DNS data is very rarely change usually save non-authoritative name server for the time of a resolver requested information in the local RAM on this new request for a so fast there. This is known as caching means. Each entry has its own expiration date ( TTL time to live ), the expiry of the cache entry is deleted after the. The TTL is it an authoritative name servers for this entry and will be determined by the change in probability of entry determined by the (frequently changing DNS data obtained a low TTL). This can possibly also mean that the name server time can provide false information in this if the data has changed in the meantime.

A special case is the Caching Only name server. In this case, the name server is responsible for any zone and must resolve all incoming requests for information about other name servers (forwarders). There are several different strategies:

Cooperation between the various name servers

This can find a non-authoritative name server information about other parts of the name space, he uses the following strategies:

Delegation

Part of the name space of a domain are often sub-domains then the name servers specifically removed from store. A name server of a domain name server knows the responsible for this subdomain’s zone file, and delegates requests to its child namespace to one of those name servers.

Forwarding (forwarding)

If the requested name space is outside its own domain, the request is forwarded to a specified name servers configured.

Resolution on the Root Server

no forwarding server configured, or is this not already answered, the root servers are consulted. To this end, in the form of a static file names and IP addresses of root servers stored the. There are 13 root servers (server A to M). The root servers will only iterative queries. They would otherwise be the number of requests simply overloaded with the.

Unlike with resolutions designed by server, such as the NetWare Name Service or the Windows Internet Naming Service are mostly on local area networks and are increasingly restricted by the Internet protocol suite displaced.

A resource record ( RR ) is the basic unit of information in the Domain Name System (DNS). He enters into ASCII representation in zone files or in compressed form in DNA transport packets or DNS cache on. Several RR types – so-called pseudo-resource records – are DNS packets transport used.

RR-format zone files

The format shown here refers to the ASCII representation, which is used in zone files. In caches or in transit, a form of identical content, but use compressed. RR types are there numbers 1-255 expressed. The same applies to class and TTL .

ASCII format: <name> [<ttl>] [<class>] <type> <rdata>

• <name> The domain name of the object to which the resource record belongs (optional)
• <ttl> time to live (in seconds). Validity of resource records (optional)
• <class> protocol group to which the resource record belongs (optional)
• <type> describes the type of resource records
• <rdata> (resource data) which describes in detail the Resource Record data (such as an IP address for an A-RR, or a host name for a NS RR)
• <length> length of following data

For some types, there are other fields that are filed directly before <rdata> (see example below: MX). The optional components may be omitted in certain cases. It is then the name server automatically queued up value of this component is used.

The permissible classes

In practice, almost without exception used. The other classes have only historical significance. From BIND servers is sometimes used CH to a name server to publish the version number.

• IN Internet
• CH Chaosnet (rarely used)
• HS Hesiod (rarely used)
• CS CSNET (no longer used)

The main RR types

• A IPv4 address of a host
• AAAA IPv6 address of a host
• AFSDB Resource Record for Cell Database server of the Andrew File System
• A6 A6 resource record of the proceedings for the partial address resolution for IPv6, now obsolete
• CERT resource record for storing certificates (see RFC 4398 )
• CNAME Canonical name for a host (the domain with the RR is an alias)
• DNAME CNAME for similar but complete domains, see RFC 2672
• DNSKEY contains a name assigned to the Public-Key – sparked by DNSSEC KEY from from the 2004 type.
• DS – is the concatenation of DNSSEC signed zones
• GPOS geographic position, out of date
• HINFO Host information ( processor type and operating system )
• ISDN ISDN number is rarely used
• LOC Location
• KEY contains a name associated with the public key – is DNSSEC since 2004 no longer used by
• MB mailbox domain name ( Experimental )
• MD mail destination (no longer in use – will now use MX)
• MF mail forwarder (no longer in use – will now use MX)
• MG mail group member ( Experimental )
• MINFO mailbox or mail list information
• MR Mail rename domain name ( Experimental )
• MX Mail Exchange – the domain responsible for this mail server
• NAPTR Naming Authority Pointer – Expansion of the A Resource Record
• NSAP Network Service Access Point
• NSEC (next secure) concatenated DNS records in DNSSEC signed zones – 2004 from the old types NXT
• NSEC3 (next hashed secure) alternative to NSEC RR without zone enumeration problem (since 2008)
• Null null resource record ( Experimental )
• NS host name of an authoritative name server
• NXT obsolete – was virtually identical to the NSEC resource record being replaced by
• OPT pseudo-RR marked a EDNS Package
• PTR domain name pointer (for the reverse mapping , assign names to IP addresses)
• RP responsible (responsible) person
• RRSIG contains a digital signature (since 2004 of DNSSEC (= DNS Security ) is used and replaced SIG)
• SIG includes a digital signature (date was up in 2004 by DNSSEC (= DNS Security uses))
• SOA start of authority
• SPF Sender Policy Framework
• SRV offered service (Service)
• Sshfp SSH fingerprint, to publish the fingerprints of SSH -bowls, see RFC 4255
• TXT freely definable text, including for Sender Policy Framework (SPF) used
• WKS Well-known service description
• X25 X.25 address is used only rarely

Each name of a domain in the Internet consists of a sequence of points separated by strings. The term top-level domain (of English. top-level domain , top-level field ‘, acronym TLD ) denotes the last name of that episode and is the highest level of name resolution dar. For example, if the complete domain name of a computer or a Web site de.example.com , it corresponds to the right member ( . com ) of the top-level domain of that name.

In the Domain Name System (DNS), the complete name and thus the TLDs also referenced and dissolved, so a unique IP address assigned. The registrar shall do so a database record of the owner of, the Whois queries over the same protocol, similar to a phone book allows.

TLDs are the IANA two main groups and a special case divided into:

• generic TLDs: generic TLD ‘s ( gTLD ‘s), divided into sponsored TLD s ( sTLD s) and unsponsored TLD s ( uTLD s)
• country-specific TLDs: country-code TLD s or ccTLD ‘s
• the infrastructure TLD ( iTLD ) . arpa (special case) and the (never been used) . root

No longer in use are the special cases . BITNET and . uucp .

Country specific TLD names always consist of two letters, general TLD names consist of three or more letters.

A list of top-level domains will all be published on the IANA. See Section Links “Root Zone Database.

Generic top-level domains

The generic top-level domains (gTLDs) are sponsored (sTLD) and non-sponsored (uTLD) Are there. The (much more important) not sponsored domains are under the direct control of ICANN and the Internet Society . The sponsored domains are controlled by independent organizations and funds. These organizations have the right to their own guidelines for the allocation of domain names used. Is one example. Mil This domain is listed by the U.S. military used exclusively.

The by far most used TLD is . com (more than 90 million registered domain names in October 2010 ). It was originally used by U.S. companies, but today it is spread worldwide. The classic in the initial phase of the defined DNS TLDs are shown in bold.

Non-Sponsor domains (uTLD)

Non-Sponsored Top-Level Domains are used by a particular group. They consist of three or more characters and are for a term that distinguishes this group.

Sponsored domains (sTLD)

Sponsored domains (engl. sponsored top-level domain , abbr sTLD ) are specific companies or organizations proposed by, the namespaces under detailed guidelines to operate them and control and enforcement rights also, that the proper and legal use of registered names with the operator should be ensured. For example, the TLD. Aero by SITA sponsored the use of contents of the aviation limited, or the use of. mobi names linked to the fact that the website provider compliance with certain guidelines should ensure that the device-independent use of web- contents are regarded as fundamental, so that, for example mobile phones can display this content.

On 26 June 2008, ICANN decided to relaxing the rules for new sponsored domains. That should apply to domain from the beginning of 2009 anyone own any possible.

Given the liberal rules for awarding the TLD . com , . net , . org and (with minor restrictions) . biz and (more recently) . name are the original meanings of these TLD has largely disappeared. Such a TLD has not necessarily indicate a corresponding use. For example, is actually the non-profit organizations intended for. Org TLD now sometimes used by commercial providers. Continue to use international, non-commercial sites like. Net (or. Org) to either on a country specific TLD, or on spread. Com need to fall back.

Special cases

There are some, mostly historical, special pseudo-domains or domains, and for certain purposes reserved to be set up for various reasons no TLD:

Country-specific top-level domains (ccTLDs)

There are over 200 ccTLDs (cc = country code), while each country is exactly two-letter code (alpha-2) according to ISO 3166 assigned. In addition, there are often their own ccTLDs for dependent territories that are geographically separated from mainland are the most.

Exceptions

• The United Kingdom uses the TLD . uk , although its ISO code is GB (GB, GBR, 826). In addition, the ISO also exceptionally encoding the UK reserved. The TLD . gb is also reserved, but is currently well except for a single registration is not used.
• The United States have, in addition . us nor the TLDs. mil ( military ). gov ( government ) as well. edu (educational institutions).
• The European Union used to. eu ccTLD one , although it is not an independent state. The coding, however, the EU has been ISO 3166 Maintenance Agency exceptional importance of this reserve through. This was done by a special decision on the basis of a perceived practical needs. In contrast to EU countries has neither a three-letter or a three-digit coding. Its member countries continue to hold their own ccTLDs and there are no country-specific subdomains of. Introduced eu.

Changes

• . Dd was for the GDR provided, however, internally at the universities of Jena and Dresden used exclusively. There was no DNS delegation in the root name servers of the IANA, the top-level domain. dd was after the turning through . de of the Federal Republic of Germany replaced.
• . Cs was used for Czechoslovakia used. It was then for the now defunct state union of Serbia and Montenegro provided. Due to continued conflict with existing Web sites and e-mail addresses of the former Czechoslovakia This was apparently not implemented on the servers. Instead it was . yu used further. With the decline in the states and their domains . rs and . me , the matter has settled. In future. Cs no longer needed.
• . Zr for Zaire in 2004 the root servers away from (now . cd ).
• . To the United States Minor Outlying Islands has been deleted 2008th
• . Yu for Yugoslavia was 30 September 2009 resolved (since 30 March 2010 is not out of reach ), since they are the two domain extensions. rs for Serbia and. me for Montenegro has been replaced.

Running out

In addition, some obsolete TLDs for reasons of accessibility still active:

• In Russia is next . ru still . su (Former Soviet Union ) is operated. There are also 18 years after the dissolution of the Soviet Union still new domains under. Su registered ^[13] . These include companies as members of the German Rhein-Sieg-Kreis ( license plate SU).
• East Timor moves from . tp to . tl and operates for an interim period both TLDs.

Unused

Allocated and are not used, mostly for lack of technical infrastructure or lack of political freedom:

• . Eh for Western Sahara ,
• . This for Somalia . The side of the Somali Network Information Center was achieved over several years, but where a sign was only that the political instability of Somalia and the general unavailability of the Internet would not awarded due to domains. SO registry has announced on its website, from 1 2011 new registrations receive April.

Conditions of the allotment

Every country has the right to own procurement guidelines for its domain set. These are by far the majority of the registries situated independently due to technical and legal requirements and needs can differ greatly.

It is for example the French TLD . fr require the domain owner residence or business has its headquarters in France.

In Germany on 23 October 2009 with the allocation of one-and two-digit and only numbers of existing domains . de begun. In the meantime, had to . com domain for at least three characters long, and one of them had to be a letter. From the early days of the Internet, there were three two-digit domains: db.de , hq.de and ix.de . (The long fourth for two-letter domain bb.de scheme was no longer registered for the time.) Volkswagen complained before the Higher Regional Court of Frankfurt am Main on the assignment of domain vw.de , which then lead to the effective date was taken into operation.

In Switzerland , only the cantons a domain with two characters from the official abbreviation is (eg ar.ch , ge.ch , ur.ch , zh.ch ). Next to it by the Swiss Federal Chancellery , the domain ch.ch operated. Apart from these exceptions must domains from at least three characters are Swiss. Exceptions are www.expo.02.ch (for six Swiss national exhibition in 2002 ) and the domain au.ch the town Au in the canton of St. Gallen .

In other cases, the second level with a few given names of possible, the actual name is then used as third-level domain (defined, for example example.co.uk ). An example is the UK uk. -domain, only the following second-level domains can be made:

• . Ac.uk – academic , educational institutions such as universities
• . Co.uk – commercial
• . Gov.uk – government , central government and regional organizations
• . Ltd.uk – limited company
• . Me.uk – presence of individuals
• . Net.uk – ISPs and other network companies
• . Nic.uk – Network Information Center , only for internal network management
• . Nhs.uk – National Health Service , state health system and its institutions
• . Org.uk – non-profit organizations
• . Plc.uk – public limited companies (listed companies)
• . Sch.uk – Schools

In addition, there are some state-used second-level domains like police.uk. , mod.uk. ( Ministry of Defence – Ministry of Defense), library.uk. british- (and bl.uk. – also for the British Library ) or . parliament.uk . These date from an earlier time and enjoy grandfathering.

Misappropriation

In particular, smaller market or those in poverty states their domains, by managing their lending policies are very liberal and apply for the registration of domains active. Here, the domain market is developing into a lucrative business, since the registration fees will be partially set well above the actual costs.

. To

One of the first such states who had registered their domains were free, 1998 Tonga with . to . The response was very good because this time were too many short and concise domains under . com is no longer available, and others had ccTLDs some very strict registration requirements. Also resulted from the ending . to interesting domain names that are nice in the short URLs could use as come.to or go.to . Today is the TLD. To be happy for torrent or warez sites used, among other reasons because the NIC does not allow holders queries, so that these domains can be registered anonymously.

Media domain

. Tv

A well-known foreign ccTLD is used . tv the State Tuvalu , as the Television will be marketed. This company was a private DotTV established that the domain market and on which the nation of Tuvalu is co-owner. This coup brought the tiny country of 50 million U.S. dollar one, the rate of $ 5 million to be paid in annual. Tuvalu domain acknowledges the past even with his own postage stamp. Tuvalu Government procured the money IT infrastructure for the main public institutions and paid the admission fee for the United Nations .

. Fm

Similarly, the ccTLD . fm the Federated States of Micronesia frequently used in the broadcasting sector, for example, when Internet radio last.fm . The abbreviation FM is in the radio for frequency modulation , in the FM radio for use is usually associated with and this is usually.

. In the

The association is an abbreviation for example, some of sites and instant-messaging services (short- IM ) are used, their TLD . in the Isle of Man is registered, such as when multi-protocol client Pidgin ( pidgin.im ).

Other abbreviations

Another special feature is the ccTLD . tk ( Tokelau ), which is often of telecommunications companies (abbreviation TK -business) is abused. . was ( Samoa ) can be a website to be marketed, although such an abbreviation is unusual. Moreover, now use some DJs (disc jockeys) the domain . dj ( Djibouti ) for their Internet presence.

The ccTLD . ag of the island nation of Antigua and Barbuda by the operator in addition to the intended use of targeted companies in Germany applied for to the legal status of a public company ) to clarify AG (. At the same time illustrates this domain, uncertainty, into which one is goes, if an “exotic” Domain registered: the entire registry was suspected power struggles for the TLD 1999-2000 no alternative destinations. for a time German – limited partnerships – Abbreviation KG was in the same way the domain . kg of Kyrgyzstan offered.

One of the newest domains, which experienced a misuse, the . ME domain of Montenegro . With it you can create meaningful domains, such as: love.me , contact.me etc. However, such can most likely very popular domains registered are simply not but be auctioned on the open registration.

Geographical areas

Also, countries or companies whose market TLDs are trying to create a market by abbreviations are invented, in a context set to the address that was not originally given. Sun markets a company domain . la ( Laos ) as the domain for Los Angeles .

Germany

The ccTLD . by ( Belarus ) is for pages with a Bavarian background, and some companies in Bavaria are used. The ccTLD country Liechtenstein . li is used by some companies and private pages from Lindau (Bodensee) used as the operators of the motor vehicle code identifying mark on LI. Similarly, in the space of Münster in North Rhine-Westphalia for the ccTLD of the British overseas territory of Montserrat . ms because this ending and the license plate (MS), applies. The ccTLD of Romania . ro by the city of Rosenheim their website used. Some in Schleswig-Holstein -based company use the ccTLD . sh of St. Helena .

Switzerland

In Switzerland, where the cantons are two-letter abbreviation always ccTLD be partially used with reference to a District of marketing to offers. Sun ccTLD be such as . ag ( Aargau , actually Antigua and Barbuda ), . be ( Bern , actually Belgium ) . sh ( Schaffhausen , actually St. Helena ) . lu ( Lucerne , actually Luxembourg ) or . sg ( St. Gallen , actually Singapore in the respective areas used).

Austria

The ccTLD . st of the island nation of Sao Tome and Principe is often called TLD for the State of Styria misused, as it is abbreviated Sun

Asturias

In the autonomous Spanish region of Asturias , the TLD of the country American Samoa . as often by individuals, companies and authorities used to presence with the name of the region to associate Internet. By city governments in the region, this TLD often used, whereby different communities only a TLD misused to achieve official web pages. Due to the small population of American Samoa in relation to Asturias, the majority of domain holders with this extension from Spain.

Specific uses

Unusual is the use of the domain . nu ( Niue ) for the pages of the Dresden’s cultural magazine , which in the local dialect of Dresden common Nu! for “Yes!” alludes. A similar magnitude is the domain in Sweden and Denmark , as in Sweden as in the Danish nu ‘now’ means. In addition, . se domains were earlier for individuals not eligible for registration.

Also very popular is the ccTLD . cc ( Cocos Islands ). This ccTLD Domains can be registered by anyone. Especially popular is the result of the minimalist ccTLD Whois system, which is the only domain registrar reveals. This operator will remain the domain virtually anonymous.

Since 2008, the ccTLD . sl ( Sierra Leone ) and marketed primarily by supporters of the virtual world Second Life used.

The technical and administrative implementation of a TLD

For each top-level domain is a group of name servers, the entire domain name space that manage the (usually by means of delegation to other servers). The domain-specific name servers are the root name server is reachable via. There is also a central database that all of this TLD located below second-level administrative domains contains information such as name and address of each domain owner. This database can be on the Whois service to be accessed.

For the operation of the server and the database is used by ICANN , an organization responsible for each domain, in Internet terminology, a domain name registry is called. For. Com is the TLD for example, the company VeriSign for. de is the DENIC . Such a registry is also the award of directly subordinate second-level domains responsible for (eg example.com ). This task is often known as registrars, delegated (see also: domain registration ).

For each TLD, there are guidelines for the assignment of second-level domains regulate. These are the websites of the respective registries available on. For some existing TLDs IDN language tables , in which all characters are listed that may be of subdomains used in the award. Thus, for example. Biz and. Org German umlauts allowed. These tables are by the IANA managed and are the sites of the cost of registries.

Alternative DNS root

There are also organizations on the Internet, the alternative name servers operate on the addition to the above, quasi-official, from the ICANN -controlled TLDs other TLDs available. A major disadvantage is that such addresses for traditional Internet users are unreachable. They too are from search engines like Google ignore. Another disadvantage is that the operator of two namespaces can collide, especially when later other top level domains are introduced.

The project OpenNIC tried alternative systems bring together, but considers the ICANN TLDs as a priority and accepts neither conflicting nor private namespaces. Their own TLDs are . glue , . indy , . geek , . zero , . oss and . parody .

Furthermore, there is the operator New.net , the number of additional Top Level Domains offers one, in which their own domains can be reserved free of charge.

An octet (English octet ) is in the computer science and digital technology, the term for an ordered list (a tuple ) of 8 bits .

History and background

As always one octet of 8 bits is, it can thus 2 ⁸ = 256 different states represented. Since modern computer byte size of 8 bits only use almost, it is often synonymous with byte used, which is not totally correct but because byte is the smallest addressable unit stands for, regardless of the number of bits, the representation of different systems are needed for its .

You should not confuse the octet with a sign that in so-called multi-byte characters can consist of multiple octets well.

The basis for today’s standard that a byte consists of eight bits, and that the smallest unit of memory addressing such a byte is a has been, from the company IBM with the S/360 architecture on-7 April 1964 down. Previously bytes in computers were also of 8 bits number of different uses have been with a.

As a measure to specify amount of data is derived from the bit unit bytes , with the proviso that there is 1 byte bits was defined as 8. Especially in standards or in the dial (in the often stop bits , are added, etc.) but often the more accurate term used octet.

In many computers, individual octets are addressed in the main memory, but also the addressing of individual bits , half-octet ( Nibbles ), double octet (16 bit) and larger groups is possible. Today, 32 – and 64-bit machine usual, the 64-bit (four or eight octets) can jointly address and 32.

An octet is 2 ⁸ = 256 different values ​​represent, which can be interpreted differently. One can, for example, is an unsigned integer value ranging from 0 to 255, a signed integer value in the range from -127 to +127 or -128 to +127 (depending on the encoding of negative numbers) or a mark or more sign store. All of these data types are only different interpretations of the same bit pattern. For example corresponds to an octet with integer value 65 in the ASCII encoding of the symbol “A”. In addition to the popular ASCII exist also proprietary character encodings such as EBCDIC which on IBM mainframes used to be.

Frequently octets, the values ​​of in hexadecimal specified, for example the decimal value “65″ as “41 ₁₆ “,” 0×41 “,” $ 41 “or” 41h “, the last three notations indicate to that it is a hexadecimal concerns. Sometimes, the value of an octet as a binary number is given, is usually the bit with the next highest value ( most significant bit , MSB ) and the right with the lowest ( least significant bit , LSB ). The counting of the bit positions usually starts with 0, that is, for example, the third bit is “bit 2″ and stands at the third position from the right.

Example of the spelling of the value 65 (binary 01000001), bit positions and to calculate the decimal value:

Value 128 64 32 16 8 4 2 1 Bit number 7 6 5 4 3 2 1 0 0 1 0 0 0 0 0 1

An octet is in two half-bytes, known as nibbles of 4 bits, divided. If we write it in hexadecimal , so a nibble corresponds to each hexadecimal digit.

Alternative use

In some cases, is also tuple of 3 bits of octet called that goes with it that, with 3 bits, eight different values, that is a octal -digit, can be represented. This name became the example of the three access permission bits (read, write, execute) in Unix -like file system used (see chmod ). In more recent descriptions of chmod term is the longer but not used to an 8-bit octet, to avoid confusion with.

As a Uniform Resource Locator ( URL ) are one type of uniform resource identifiers (URIs). URLs identify and locate a resource by the access method to use (for example, the used network protocol such as HTTP or FTP ) and location (English location ) of the resource in computer networks . In common usage they are also called Internet address designated where it (the colloquial frequent equating of Internet and World Wide Web ^[2] following) usually specially URLs websites are meant.

As the first and most common type of URLs are URIs, the terms are often interchangeably used. The difference is in simple terms is that the URIs for the actual access to resources in the context of the Internet URL syntax thought to the mere naming any resources extend from – so, for example, telephone numbers

scheme

Determines method of the resource should be addressed with any technical. Is generally, but not necessarily identical with the used network protocol over which the resource can be located. Examples include HTTP , HTTPS or FTP , as well mailto (for writing an e-mail) or file (to access local files).

scheme-specific-part

Depending on the scheme are different specific information required, respectively. possible. The following is an example of the HTTP shown for.

user / password

If required, a login of username (username) and password ) are transmitted password (. These are separated by another colon, separating the domain with an at sign ( @ ) prefix.

Although for this example the protocol HTTP was selected, specifying the username and password as part of the URL just not part of the HTTP specification! Current Browser URL syntax accept this though, but ask the user for whether he with the specified data register would really be. The Internet Explorer 6 (Windows XP SP2) is out of line here, by this URL syntax flatly rejected as faulty. With a registry entry you can force him to the same behavior as previous version 5.5 to show his: They take over the login information without permission and pass it directly to the server.

Some other protocols such as FTP , form is an indication of the user data shown in the other hand, entirely correct and that the standards covered by.

host

The host component is in the form of an IPv4 address in decimal notation separated by dots, in the form of an IPv6 address in hexadecimal notation separated by colons and square brackets in or as a FQDN listed.

port

The type of ports allows the control of a TCP / IP ports. If no port is specified, the default port of each protocol used – for example, HTTP 80, HTTPS on 443 and when FTP is 21

url-path

The path describes a particular resource (this may be with the structure of the target system such as cover, or about a file or directory) on the server . The path may be empty. An empty path can be replaced by a slash and is optional for this equivalent.

The interpretation ( file or directory , text file, deliver or script to run ) is left to the server. A typical example of the freedom of interpretation is the behavior at the request of the path / a client: Depending on your server returns the contents of a particularly excellent as the file (like / index.html , / README , / HEADER ), without this the requesting client is apparent. Similarly, the server, however – depending on the protocol – also explicitly associated with this item forward or a directory listing output.

searchPart

In the case of HTTP, after the actual resource indicators – separated by a question mark – a query string to follow. Thus, additional information is transmitted, the server or can be processed on the client side.

fragment

After a double cross , a part of the resource references (typically an anchor in an HTML page, which then automatically heruntergescrollt is: The URL ” # http://example.com/dokument.html absatz3 “would be the third document in the fictitious sales jump.

Examples

• ftp://hans:geheim ftp.example.org @ FTP with user and password
• http://de.wikipedia.org website without a path (called the ” Home “)
• http://de.wikipedia.org/wiki/Uniform_Resource_Locator website with path
• mailto: nobody@example.org for writing an e-mail to the given email address (mail client opens the default with a new, empty mail in which the TO address is already filled)
• news: alt.hypertext display of a Usenet newsgroup (generic, without specifying the network protocol NNTP )
• nntp: alt.hypertext ad to a Usenet newsgroup (with details of the network protocol NNTP)
• telnet: example.org start a Telnet session
• file: / / / C: / temp / test.txt access to a local file

Language

The acronym URL is in the German language usually with a female articles , with a male article uses occasionally. The choice of gender depends on whether it is in line with the German translation of ” the address “) which is feminine (or by the rule that words-or “(here” Locator “) in the German masculine are always” on.

URLs in text

RFC 3986 , Appendix C, recommends URIs (and thus URLs) in texts

• independently on a line
• with double quotes "http://example.com/" or
• with angle brackets <http://example.com/>

against the context and especially against the punctuation of the sentence to distinguish.

History

Name and standardization

In the early days of the WWW (from the end of 1990) was found in the documentation on info.cern.ch first no dedicated name for the addressing of Web pages, the subject was only descriptive than “W3 document address” , “W3 name” , “W3 address “ or “Hyper Text name” . documented at the time specified (and in the first websites used) the form of address equivalent to the but even the later as “URL” standardized form, in the standardization process, although changes were considered because of the now-advanced distribution of the WWW, but again rejected.

In the summer of 1992 tried to Tim Berners-Lee at the IETF meeting in Boston to call into life working group, the documents on the Web should standardize the access. He proposed as names Universal Document Identifier (UDI) prior to, presentation of a general Internet standard should be defined by it under what. But the name was too arrogant “criticism”, mainly on the word “universal” : universal (comprising) was dt. Instead, the group was of the more modest term “uniform” : uniform () dt proposed. Furthermore, was the “Document” by “resource” replaces underscore that the Web should be integrated with other information systems. The URI working group came about after all, and yet another name change for the to be defined standard was adopted: “identifier” was “Locator” replaced emphasize that there are web addresses not permanently registered addresses concerns.

the group was the first – - yet informal manner due to the conflicting standards draft RFC 1630 in June 1994 by Berners-Lee presented. in the first He names names of Berners-Lee the favorite , “Universal Resource Identifiers” in the title and already defined the terms URI, URL and URN. In December 1994, by the group in RFC 1738 standard for “Uniform Resource Locators (URL)” published.

Components

Berners-Lee borrowed some of the individual constituents aware of existing systems to new users as Web addresses directly familiar, respectively. logically appear to be:

• The path part ( http://www.example.com / foo / bar / baz.html ) quotes directly the path syntax in UNIX file systems . ^[20]
• The double-slash notation introduced with the host is from the syntax of the network file system from Apollo Domain / OS , the paths to remote hosts using the model / / example.com / foo / bar / ... have been addressed.
  
• This with a hash of the fragment is marked in the USA standard notation for apartment – and suite numbers in mailing addresses borrowed: “12 Foo Avenue # 34″ stands for “Foo Avenue No. 12, Apartment 34″, and accordingly does foo.html # bar ” part (section, chapter …) bar in the document foo.html . ”

An IP address is an address in computer networks , which – like the Internet – on the Internet protocol IP) based (. You will be assigned devices that are network connected and makes the devices so addressed and so accessible. The IP address can be individual or a group of receivers called a ( multicast , broadcast ). Conversely, a computer multiple IP addresses assigned to it.

The IP address is used, data from the sender to the intended recipient to be able to transport her. Similar to the mailing address on an envelope are data packets provided with an IP address, uniquely identifies the recipient. Because of this address, the “Post”, the router decide the packet should be transported in the direction which. Unlike postal addresses IP addresses are not tied to a specific location.

The best known of today’s common notation IPv4 addresses consist of four numbers, the values ​​of 0-255 and can take from one point to be separated with, for example, 127.0.0.1 . Technically, the address is a 32-digit ( IPv4 ) or 128-digit ( IPv6 ) binary number .

Fundamentals

To communicate between two technical equipment to build one, each of the devices must be able to, the other device to send data. For this data to arrive at the correct remote site, it must be clearly identified (addressed) are. This is done in IP networks with an IP address. Thus, for example, a Web server via a web browser directly addressed by its IP address. The browser asks for this domain name , like “www.example.com”, IP address from any name server , and then speaks directly to the Web server’s IP address “198.51.100.42″ in As.

IP address in IP packets

Each IP packet starts with an information area for the transport through the IP layer , the IP header. This header contains two fields, in which the IP addresses of both the sender and the recipient to be entered before the data packet is sent. The mediation is done on layer 3 in the OSI model , the network layer .

Structure

IPv4

Since the introduction of version 4 of the Internet Protocol used mainly IPv4 addresses consist of 32- bits , ie, 4 octets (bytes) . This 2 are ³² , that is 4,294,967,296 addresses displayed. In dotted decimal notation , the 4 octets than four points separated by decimal integers in the range 0-255 in written,

Example

130.94.122.195 .

IPv6 – new version with a larger address space

Due to the rapidly growing demand for IP addresses is likely that the usable address space of IPv4 will be exhausted sooner or later. Mainly for this reason, IPv6 developed. It uses 128 bits to store addresses so that there are 2 ¹²⁸ = 256 ¹⁶ (= 340,282,366,920,938,463,463,374,607,431,768,211,456 ≈ 3.4 × 10 ³⁸ ) addresses displayed. This number is sufficient for every square millimeter of the surface at least 665.570.793.348.866.944 (= 6.65 × 10 ¹⁷ ) ^[1] provide IP addresses.

Since the decimal ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd and difficult to handle would be confusing, to set IPv6 addresses in hexadecimal dar. To further simplify this presentation, two address octets are combined and the groups represented by separate colon. XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX: XXXX .

Example

2001:0 db8: 85a3: 08d3: 1319:8 a2e: 0370:7344

Network part and device part

Each IPv4 address is a subnet mask , any IPv6 addresses by specifying the prefix length , in a network and a device component (“host part”) separately. The network mask, ie the prefix, it indicates the address bits are divided on what must be. The network mask of the masked or the prefix length specified bits (network part) in all hosts (computers) of a subnetwork identical. The information whether a device is in the same subnet (ie the same network part of IP address), is a host of needs in order routing to make decisions (see next section).

Example

(Classless) IPv4 Address 130.94.122.195/27

              Decimal Binary calculation 10,000,010 01,011,110 01,111,010 130 094 122 195 IP address 11,000,011           ip-address
network mask 255.255.255.224  11111111 11111111 11111111 111 00 000       AND  netmask
Netzwerkadr. 130 094 122 192  10,000,010 01,011,110 01,111,010 110 00000 = network part

10,000,010 01,011,110 01,111,010 130 094 122 195 IP address 11,000,011           ip-address
network mask 255.255.255.224 11111111 11111111 11111111 111 00 000
                               00000000 00000000 00000000 000 11 111        AND ( NOT  netmask ) Equipment Part 3 00000000 00000000 00000000 000 00 011         = Receptacle

With a netmask of 27 bits set by a network address is 130.94.122.192 . There remain 5 bits and thus 2 ⁵ = 32 addresses for the device component. Of these, nor ever will be an address for the network itself and the broadcast is required, 30 addresses for devices that are available.

Routing

If a device to send a IP packet, the network address parts of the source IP address and destination IP compared. If they match, the destination host is located in the same network and the packet is sent to the recipient directly. In the case of Ethernet networks is the ARP (Address Resolution Protocol) to find the hardware address. The ARP works on the second layer of the OSI model and is establish the connection to the first layer.

If the network part but not identical, so a routing table the IP address of a router (next hop) is searched and sent the packet to this router. This has one or more interfaces in contact with other networks and routes the packet using the same method more – he consulted his part his own routing table and sends the packet to the appropriate next router or to the target. Until the terminal can package many networks and routers go through that. Running through a router is also hop (jump) called the routing method next hop routing .

A router has for each interface its own IP address and subnet mask that belongs to the respective network. Each IP packet is routed separately. The source and destination address in the IP header are set by the station and remain unchanged during the entire journey.

Special IP addresses

Special IPv4 addresses to RFC 3330 :

After fulfilling this list 622 199 809 of around 4.3 billion IPv4 addresses, or 14.5% of all possible IPv4 addresses a particular purpose.

1. The network 127.0.0.0 / 8 refers to the local machine ( loopback address ). That power is often the area address 127.0.0.1 with the hostname localhost responsive. Addresses from this range are used to communicate a client with a server process on the same computer. With command line commands such as ssh localhost or ftp 127.0.0.1 , the local server computer to be addressed one on their functioning in order to test such.
2. The special address 255.255.255.255, the highest device address in the network also be used as a broadcast address next. This network parameters is sending broadcasts without knowledge of other possible. This is for protocols such as BOOTP and DHCP important.

Thus there are three IP address types:

• Unicast : Send to an individual on the Internet (normal addressing).
• Broadcast : send to all devices on the same network ( subnet ). This is in IPv6 Multicast replaced.
• Multicast : Send some products on the same network (or devices in the multicast backbone network ).

No longer reserved IP addresses

With the RFC 5735 addresses were about 50 million IP-enabled. The reservation of the following address ranges has been lifted and released for distribution.

DNA – translation of computer names to IP addresses

On the globally available domain name system (DNS) names to IP addresses can (and vice versa) are resolved. The name www.example.com is for example the IPv4 address 208.77.188.166 , the name www.ipv6.uni-muenster.de the IPv6 address 2001:638:500:101:2 e0: 81ff: ​​fe24: 37c6 .

Assignment of IP addresses and network areas

IANA – Internet Assigned Numbers Authority

The assignment of IP networks in the Internet is used by the IANA regulated. In the early years of the Internet networks were IPv4 addresses, or in large blocks from the IANA to organizations, companies or universities awarded directly. For example, the area was the 13.0.0.0 / 8 and therefore 16,777,216 addresses of Xerox Corporation allocated. Merck & Co. received from the IANA also an area of 16,777,216 addresses ( 54.0.0.0 / 8 ), as well as IBM ( 9.0. 0.0 / 8 ). The only German company which has a / 8 range has been allocated, the debis AG ( 53.0.0.0 / 8 ). Today, the IANA allocates blocks to regional registries.

RIR – Regional Internet Registry

Since February 2005 there are five regional registries, the Regional Internet Registries ) are called RIR (:

• AfriNIC (African Network Information Centre) – responsible for Africa
• APNIC (Asia Pacific Network Information Centre) – responsible for the region Asia-Pacific
• ARIN (American Registry for Internet Numbers) – North America
• LACNIC (Regional Latin American and Caribbean IP Address Registry) – Latin America and Caribbean
• RIPE NCC (Réseaux IP Européens Network Coordination Centre) – Europe , Middle East , Central Asia .

LIR – Local Internet Registry

The Local Internet Registries (LIR) said local authorities give the award to them from the RIRs allocated addresses to their customers. The object of the LIR usually meet Internet Service Provider . LIR customers can either retail or other (sub) providers are.

The addresses of customers can be either permanently assigned to the ( static IP address, fixed IP address ), and Internet connection are dynamically allocated structure for the ( dynamic IP address, dynamic IP address ). Permanently assigned addresses are used primarily with dedicated lines used, or if server address should be operated on the IP.

Which customers or any Local Internet Registry IP address or a network has been assigned, can be on the Whois databases of the RIRs to determine.

Private networks

In private, local networks ( LAN ) allows one IP addresses are assigned. But should the IPv4 addresses from the for RFC 1918 called private networks are used (for example, 192.168.1.1, 192.168.1.2, ... ). These addresses are not assigned by the IANA and the Internet continue to not routed. In order to still allow an internet connection to be in a router using Network Address Translation that LAN internal addresses public, valid in the Internet IPv4 addresses translated to. For packages to arrive addressed to the public address, public address is in turn translated back into private address.

Net classes

Originally, IPv4 addresses have been in network classes A to C with different network masks divided by. Classes D and E were designed for specific tasks. Due to recent increases in routing tables, routing was 1993, the classless CIDR ( Classless Inter-Domain Routing ) is introduced. So that it does not matter which network an IPv4 address class belongs.

Device configuration

Manual configuration

For administrators there are programs to display the IP address and configure. unixoid operating systems use this command, the ifconfig for Linux, ip available, DOS or Windows use, depending on the version, type ipconfig or winipcfg .

Examples

The network interface eth0 is assigned the IPv4 address 192.168.0.254 in a / 27 subnet.

• Unix (FreeBSD, Mac OS X): ifconfig eth0 192.168.0.254/27
• Linux : ip addr add 192.168.0.254/27 brd + dev eth0
• Linux (old): ifconfig eth0 192.168.0.254 broadcast 192.168.0.255 netmask 255 255 255 224

The part “broadcast 192.168.0.255″ or “brd +” are optional. (“Brd +” stands for the automatic calculation of the broadcast address, it can also be given a specific address. Ifconfig calculates the broadcast address in newer versions automatically, eg from FreeBSD 4.x).

Automatic configuration

Through protocols such as BOOTP or DHCP IP addresses when booting the computer by a corresponding server assigned. On the server administrator to a range of IP addresses defined, from which other computers can see an address at startup. This address is to the computer lease . Computers that may need fixed addresses, the Ethernet network via its MAC address to identify and obtain a permanent address.

The advantage here is the central management of the addresses. If after installing the operating system provides for the automatic configuration, no further settings for network access will be made ​​longer. Mobile devices such as laptops can share addresses, if not all devices are connected to the network simultaneously. In addition, they can not change the configuration as needed in different networks sample company, customer networks, home networks) are integrated to the (.

For IPv6, there is also the possibility of auto configuration , the server does not need.

Dynamic addressing

If a host connection with a new network a new IP address is assigned to each, it is called dynamic addressing . In the LAN area, the dynamic addressing via DHCP widespread. In the Internet sector is dynamic addressing mainly by Internet Service Providers (ISP) used the Internet access via dial-up lines to offer. They use dynamic addressing via PPP or PPPoE .

Advantage of dynamic addressing, is that far fewer than one IP address per customer needs is the average, there are never any customers online simultaneously. A ratio of 1:10 to 1:20 is common. The RIPE NCC requires its LIRs evidence of the use of their assigned IP addresses. A fixed allocation of addresses is accepted only in justified cases, for example for the operation of servers, or for accounting purposes.

With DSL connection of customer to use the official provider usually also dynamically assigned IPs. Due to the common practice that the DSL router provider associated with the remains always (24 hours a day, possibly with forced separation and automatic reconnection), usually is the corresponding router always assign the same IP (see DynDNS ).

Static addressing

Static addressing is basically used in applications where dynamic addressing is not technically possible or not meaningful. Thus obtained in LANs, for example, gateways , servers and network printers usually fixed IP addresses. In the Internet access area is for static addressing in particular router on dedicated lines used. Also for Machine-to-machine communications, especially in mobile communications ( GPRS ) are increasingly static addressing. Static addresses are usually configured manually, but also has automatic addressing (see above) are assigned.

Enter multiple addresses on a network card

Usually, each network interface (eg network card) of a host to an IPv4 address assigned exactly. In some cases (see below) however, it is necessary to interface more IPv4 addresses to assign one. This is known as IP aliasing means. A number of IPv4 addresses on one NIC others used in to several of the same services it to operate in parallel in order from different subnets reachable to make host one or a service logically be separated from the host so that he – with its IPv4 address and transparent Hardware can be moved – to another client for the.

Example (FreeBSD)

The network interface fxp0 get the IPv4 address of 192.168.2.254 with a / 26 subnet as an alias

ifconfig fxp0 alias 192.168.2.254 netmask 255 255 255 192

On Linux, just the same command as above

ip addr add 192.168.2.254/24 dev eth0

used to add more addresses.

For IPv6, the binding of multiple addresses to a network interface the rule, for example, a link-local operators to find a global address and dynamically assigned prefixes in addition to fixed or IPv6 addresses on the same host multiple Internet providers to have available. Furthermore, the above reasons apply as for IPv4.

Different networks on one physical network

On a physical network (eg Ethernet), different networks (with different network address part) is placed and used simultaneously. This will be used, inter alia, if later, the network should be split up or if previously separate networks are combined.