Primary and Secondary DNS

There are two main types of DNS servers.

Primary DNS Servers :

The Primary DNS server is referred to as master server.  Also known as Primary DNS Zone

• The primary server gets the data for its zone which stores and maintains the files.
• It is the read/write copy of the DNS database.
• It is responsible for creating, maintaining and updating the zone files which stored on a local disk.
• It is also responsible for communicating with the secondary server.
• The process of Communicating with the secondary server is called Zone transfer.

Secondary DNS Servers :

The Secondary DNS server is referred to as slave server. Also Known as Secondary DNS Zone.

• The server gets the data from the primary zone immediately after being set.
• It  gathers complete information from the primary and stores in a local disk.
• The secondary server neither creates nor can update the zone files.
• It is the read only copy of the DNS records.
• If updating is required, it must be done by the primary sever which sends the updated version to the secondary data.
• Secondary server can be set up as a master server and can pull data from the primary server.

The zone transfer process.

• A master DNS server sends notification of zone changes to the secondary server or servers.
• The secondary server queries a master DNS server for changes to the zone file.