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1、Copyright, 2002 Michael SonntagE-Mail: sonntagfim.uni-linz.ac.at WWW: http:/www.fim.uni-linz.ac.at/staff/sonntag.htmMag. Dipl.-Ing. Dr. Michael SonntagDomain Name System / ICANNDomain Name System / ICANNLegal and Technical Aspects of E-Commerce, Budapest, 7.-11.10.2002Michael Sonntag2Legal and Techn
2、ical Aspects of E-CommerceQuestions?Questions?Please ask them immediately!?Michael Sonntag3Legal and Technical Aspects of E-CommerceContentlWhy the need?lStructure of DNlName serverslAddress resolutionlWHOIS databaselProtection of DN: Name, unfair competition, trademarks, copyrightlICANN History, ta
3、sks, organization, problemslUniform DN Dispute Resolution PolicyMichael Sonntag4Legal and Technical Aspects of E-CommerceWhy the need?lComputers in the Internet are (currently) addressed by 4 bytes (e. g. 140.78.100.130)lTo ease remembering, names are given to them Requires mapping from name to numb
4、er and in reverse E. g. www.fim.uni-linz.ac.atlEach name is worldwide unique Disputes over “precious” names Disputes between name holders from different regions Disputes over exploitation schemes Disputes over restraint of competitionMichael Sonntag5Legal and Technical Aspects of E-CommerceThe struc
5、ture of Domain Names (DN) (1)lThe DNS is a directed acyclic graph This is only the logical structure Physical structure is independent Server responsible, Location of servers, owners, Each node has a name; must be different from all siblings Each node contains an arbitrary number of resources Can al
6、so be empty! Name of a node: 1-63 characters Often: 3 characters minimum length May contain: Letters (case-independent), numbers, “-” Must start with a letter and end with a letter or a numberMichael Sonntag6Legal and Technical Aspects of E-CommerceThe structure of Domain Names (DN) (2)lA DN is the
7、concatenation of all node names from the leaves up to the root, separated by dotslRoot is only node without a name (usually omitted) Full name: www.fim.uni-linz.ac.at. Relative name: www.fim.uni-linz.ac.at or www.fim To complete them, the standard domain is attachedlTwo/Three types of Top Level Doma
8、ins (TLD) Generic TLDs (gTLD): According to ressources Country TLDs (cTLD): Country of registration Need not be country of server, owner, products offered, ! Infrastructure Domain: .arpaMichael Sonntag7Legal and Technical Aspects of E-CommerceThe structure of Domain Names (DN) (3)fim.uni-linz.ac.at.
9、Michael Sonntag8Legal and Technical Aspects of E-CommerceTop Level Domains (TLD)lGeneric TLDs com, int, edu, gov, mil, org, net New gTLDs: aero, biz, coop, info, museum, name, prolNEW gTLDs can be “sponsored” or “unsponsored”: Sponsored: Additional organization managing domains Additional policies e
10、xist: e. g. restrictions who can obtain a name Managed for benefit of a smaller group Sponsored: aero, coop, musuem Unsponsored: Managed fully by ICANNlCountry TLDs 2-letter ISO country codes (ISO-3166)Michael Sonntag9Legal and Technical Aspects of E-CommerceWho actually controls the DNS?lThere are
11、13 root name servers They control the “existence” of a country / gTLD 10 in the USA, 1 Sweden, 1 UK, 1 Japan Named a.root- - m.root- Operated on a free-of-charge basis; sponsored by governments or companieslUsing other name servers, a completely different hierarchy can be used This could even overla
12、p: Same name, different addressMichael Sonntag10Legal and Technical Aspects of E-CommerceName Servers (1)lA new domain can only be created with approval (and support) by the parent domainlEvery domain can create arbitrary subdomains “Authoritative servers” are responsible for managing subdomains “re
13、al” anwers Caching servers only store answers from other servers Changes to a name (new, different address) take some time to propagate (usually several minutes, up to 1 day) Each domain must possess at least 2 name servers If one fails, names can still be resolvedMichael Sonntag11Legal and Technica
14、l Aspects of E-CommerceName Servers (2)“Glue” needed if NS for subdomain is not directly in subdomainMichael Sonntag12Legal and Technical Aspects of E-CommerceAddress Resolution (1)lEvery host knows its “own” nameserver(s) (2-3) Usually within the domain or at the access providerlIf a name is unknow
15、n, this nameserver is asked In cache, or known: direct answer Recursive query: This nameserver asks a root-server and then more specific nameservers and returns the end result to the client Iterative query: Client must ask root servers itself (and also do the rest of the lookup Low-level nameservers
16、: Usually recursive Root-servers, gTLDs, cTLDs: Always iterativeMichael Sonntag13Legal and Technical Aspects of E-CommerceAddress Resolution (2)www.myCompany.bizHostName- server1) ?ns.myCompany.bizName- server2) .com?a.root-Name- 3) ?Name- 4) ?1) Recursive query2-4) Iterative queriesWhere from?Michael Sonn
