Archive for January 25, 2012

DNS keeps track of Information in Zones. Essentially, a zone is a flat-file database for a particular domain, such as The zone can contain different rexord types, all of which can be queried by clients:

> A : Which i a Host Address record – this resolves a single host name. suck as www, to an IP address.

> CNAME : or Alias – This resolves a name such as www to an actual host name, such as www1. think of it as a nickname for a computer -“www”, for example, is easier to remember and more standardized than a computer name like “w4salwin” which is what a Web Server’s real name might be.

> MX : or Mail Exchanger – This provides the name of the mail server for a Domain. Multiple MX records can be provided for fault tolerance or load balancing and a prioroty assigned to each. Clients, Such as sending mail servers, will attempt to contact the server in the MX record with the lowest-Numbered Priority.

> AAAA – This maps an IPv6 IP address to a host name.

> SRV: or Service – This provides the IP address of  one or more servers providing a particular service. AD uses SRV records to allow clients to locate Domain Controllers, among other things.

> SOA: or Start of Authority – This Special record indicates that the DNS Server hosting the zone is authoritative for the zone and is the primary source of name resolution for hosts within that domain.