Sunday, January 11, 2009

DNS zone types

Dns zones are used to get domain name and it's information. There are three types of zones in a Domain Name System which provide name information for a domain.

DNS Primary zone:

A DNS zone is called primary zone if the DNS server for the zone is the primary source of information about the zone. The DNS server stores the master copy of zone data in a local file or in Active Directory Domain Services (AD DS). By default, the primary zone file is named zone_name.dns and it is located in the %windir%\System32\Dns.

DNS Secondary zone:

A zone is called a secondary, if it is secondary source of information about a zine. The zone information can be obtained from another remote primary zone.

Note: 1. The Secondary DNS zone cannot be stored in Active Directory Domain Services (ADDS) Because a secondary zone is merely a copy of a primary zone.

2. The Secondary DNS server must have access to the remote DNS server that hosts the Primary DNS zone.

DNS Stub Zone:

A zone is called a stub zone, if the DNS server for the zone maintains only the information about authoritative name servers of the zone. This zone's complete information can be obtained from another DNS Server which can be primary dns server for the zone. This DNS server should have access to the remote primary DNS server to get updates on authoritative name server of the zone.

A stub zone can be used for the following scenarios:

  • Delegates zone information regularly. A DNS server that hosts both the parent zone and the stub zone for one of its child zones will maintain a current list of authoritative DNS servers for that child zone.

  • Improve name resolution. Using the stub zone's list of name servers, name resolution is easy without having to query the Internet or an internal root server for the DNS namespace.

  • Easy of administration. DNS stub zone's authoritative name resolution eliminates the use of secondary DNS zones by distributing a list of the authoritative DNS servers for a zone.

Note:However, stub zones can't eliminate secondary dns zones for enhancing redundancy and load sharing.


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