BIND&DNS Notes
Contents
What is DNS (Domain Name System)?
- a hierarchical, distributed database
- for mapping Internet host names to IP addresses and vice versa
- provides mail routing information
What are the components in the DNS?
- DNS Clients
- resolver library
- DNS server
DNS clients (e.g. Web browser is one of those) look up information in the DNS by calling a resolver library, which sends queries to one or more name servers and interprets the response.
- Domains and Domain Names
- Zones
DNS Servers
Authoritative Name Servers
A name server which contains the complete data for a zone.
- The primary master DNS server: maintains the master copy of the zone data
- Slave DNS servers: (aka secondary servers) load the zone contents from another server using a replication process known as zone transfer.
Non-authoritative Name Servers
- Caching Name Server, or recursive name server
A name server which performs recursive lookups for local clients. Recursive name servers normally cache the results of the lookups they perform to improve performance.
- Forwarder
Some a caching name server may not perform the recursive lookup all by itself. It can forward some or all of the queries to another caching name server, commonly referred to as a forwarder.
Root Zone and Root Name Server
Root Name Servers
- named.cache or
- named.root
Root Zone
- root.zone and
- root.zone.gz (gzip of root.zone)
