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CPET 355 Data Communications & Networking. 7. The Application Layer: Domain Name System Paul I-Hai Lin, Professor Electrical and Computer Engineering Technology Purdue University, Fort Wayne Campus. The Application Layer (TCP/IP-based). Introduction TCP/IP Application Suites
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CPET 355Data Communications & Networking 7. The Application Layer: Domain Name System Paul I-Hai Lin, Professor Electrical and Computer Engineering Technology Purdue University, Fort Wayne Campus Prof. Paul Lin
The Application Layer(TCP/IP-based) • Introduction • TCP/IP Application Suites • DSN – The Domain Name System • Electronics Mail • The World Wide Web • Other TCP/IP applications? Prof. Paul Lin
Web Site References for Standards • W3C World Wide Web Consortium - http://www.w3.org/ • Internet Architecture Board (IAB) of Internet Society (http://ww.isoc.org/index.html) • Internet Engineering Task Force - http://www.ietf.org/ • RFC Pages -http://www.ietf.org/rfc.html • International Organization for Standardization - http://www.iso.org/iso/en/ISOOnline.frontpage • Internet Corporation for Assigned Names and Numbers - http://www.icann.org/ Prof. Paul Lin
Request For Comments • <http://ietf.cnri.reston.va.us/rfc/> • Working notes of the Internet research and development community • A RFC may be recommended by the IETF to become a standard • Web site that hold archives relate to the Internet and IETF Prof. Paul Lin
TCP/IP Applications • Telnet: Remote Login (RFC 854) • TFTP: Trivial File Transfer Protocol • FTP: File Transfer Protocol (RFC 959) • File Access using NFS (Network File Systems) and RPC (Remote Procedure Call) Prof. Paul Lin
TCP/IP Applications • Telnet: Remote Login (RFC 854) • TFTP: Trivial File Transfer Protocol • FTP: File Transfer Protocol (RFC 959) • File Access using NFS (Network File Systems) and RPC (Remote Procedure Call) Prof. Paul Lin
The Domain Name System • The Need for Unique Name Spaces • Binding the names and IP addresses • Flat name space (no structure, a flat table) • Hierarchical name space (tree type: root, node) • The DNS Purpose: • mapping host names and e-mail destinations to IP addresses • Map domain names onto resource records • Resource Record (five-tuple) Domain_name Time_to_live Class Type Value Prof. Paul Lin
The Domain Name System • A hierarchical, domain-based naming scheme, and a distributed database system • A distributed Internet directory service • RFC 1034 – Domain Name: Concepts & Facilities, 1987 • RFC 1035 – Domain Name: Implementation and Specification, 1987 Prof. Paul Lin
Domain Name Space • Each node in the DNS tress has a “Label” • A domain is a subtree of the domain name space • Each node has a “Domain Name” • ICANN (www.icann.org) Internet Corporation for Assigned Names and Numbers Prof. Paul Lin
Distribution of Domain Name • Two Top Level Domains before year 2000: Generic and Countries • In Nov. 2000, ICANN approved • Four new general purpose top-level domains: • biz (business), info (information), name (people’s name), pro (professions) • Three specialized top-level domains: • aero (aerospace industry), coop (co-operatives), and museum Prof. Paul Lin
Domain Name Space • The Country Domain - ISO 3166 • Top-Level Domain Name Examples (Generic) • com - commercial • edu - educational institutions • org - nonprofit organizations • net - network providers • gov - the U.S. federal government • mil - the U.S. armed forces • int - certain international organizations, www.un.int Prof. Paul Lin
Domain Name Space • Top-Level Countries Domain (http://www.iana.org/cctld/cctld-whois.htm) • us - U.S. • mx - Mexico • tw - Taiwan • kr - Korean • Jp - Japan • nl - Netherlands • br - Brazil Prof. Paul Lin