G lcsmitedu 85 neither manageable nor ecient as

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Unformatted text preview: Mul8ple levels, e.g. full name à༎ email à༎ IP address à༎ Ethernet address •  Resolu8on (or lookup) is mapping a name to an address Name, e.g. “Andy Tanenbaum,” or “flits.cs.vu.nl” Lookup Address, e.g. “Vrijie Universiteit, Amsterdam” or IPv4 “130.30.27.38” Directory 101 4 11/26/13 Before the DNS – HOSTS.TXT •  Directory was a file HOSTS.TXT regularly retrieved for all hosts from a central machine at the NIC (Network Informa8on Center) •  Names were ini8ally flat, became hierarchical (e.g., lcs.mit.edu) ~85 •  Neither manageable nor efficient as the ARPANET grew … 102 DNS •  A naming service to map between host names and their IP addresses (and more) –  www.uwa.edu.au à༎ 130.95.128.140 •  Goals: –  Easy to manage (esp. with mul8ple par8es) –  Efficient (good performance, few resources) •  Approach: –  Distributed directory based on a hierarchical namespace –  Automated protocol to 8e pieces together 103 5 11/26/13 DNS Namespace •  Hierarchical, star8ng from “.” (dot, typically omifed) 104 TLDs (Top- Level Domains) •  Run by ICANN (Internet Corp. for Assigned Names and Numbers) –  Star8ng in ‘98; naming is financial, poli8cal, and interna8onal J༄ •  22+ generic TLDs –  Ini8ally .com, .edu , .gov., .mil, .org, .net –  Added .aero, .museum, etc. from ’01 through .xxx in ’11 –  Different TLDs have different usage policies •  ~250 country code TLDs –  Two lefers, e.g., “.au”, plus interna8onal characters since 2010 –  Widely commercialized, e.g., .tv (Tuvalu) –  Many domain hacks, e.g., instagr.am (Armenia), goo.gl (Greenland) 105 6 11/26/13...
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