---
title: "dns"
aliases: 
tags: 
- cosc203
---

record has four fields
- name
- value
- type
- ttl

meaning of name an value are dependent on type

Types
- A
	- name - hostname
	- value - ipv4 address for the hostname
	- hostname to ipv4 mapping
- AAAA
	- same as A but ipv6
- NS
	- name - domain (e.g., otago.ac.nz)
	- value  - hostname of authoritave DNS server that knows how to get the IP address for hosts in the domain
	- used to route DNS queries further along the query chain
- CNAME
	- value - canonical hostname for the alias hostname Name
	- can provide querying the cananical name for a hostname
- MX
	- value - canonical name of a mail server that has an alias hostname name
	- allows the hostnames of mail servers to have simple aliases
	- allows a company to have the same aliased name for its mail server and for one of its other servers (e.g., web server)
	-