COMPSCI 132 Study Guide - Final Guide: Message Transfer Agent, Hostname, Mac Address

• School: UC-Irvine
• Department: Computer Science
• Course: COMPSCI 132
• Professor: Athina Markopoulou

Document Summary

Network layer: a distributed database implemented in a hierarchy of dns servers, an application-layer protocol that allows hosts to query the distributed database. Dns protocol runs over udp and uses port 53. Host aliasing: obtain the canonical hostname for an alias hostname. Mail server aliasing: obtain the canonical hostname for an alias hostname. Load distribution: busy sites have replicated servers which have different ip addresses. Dns returns set of the ip addresses but rotates them to distribute the traffic among replicated servers. Application in user"s host needs to translate a hostname to an ip address. Application will invoke client side of dns, specifying the hostname that needs to be translated. Dns in user"s host sends query message into the network. Dns in user"s host receives a dns reply message with the ip address and passed onto application. Three classes of dns servers: root dns servers top-level domain (tld) dns servers authoritative dns servers. Header section (12 bytes): number of fields.