Dns slave not updating

On a second or subsequent request for the same data the Caching Server (Resolver) will respond with its locally stored data (the cache) until the time-to-live (TTL) value of the response expires, at which time the server will refresh the data from the zone master.If the caching server (resolver) obtains its data directly from a zone master it will respond as 'authoritative', if the data is supplied from its cache the response is 'non-authoritative'.

dns slave not updating-65dns slave not updating-14dns slave not updating-11

Diagram 1 DNS Master Master status is defined in BIND by including 'type master' in the zone declaration section of the file as shown by the following fragment.

When a master DNS receives Queries for a zone for which it is authoritative then it will respond as 'Authoritative' (AA bit is set in a query response).

There are now a number of alternate Open Source DNS servers some of which stress performance.

These servers typically do NOT provide caching services (they are said to be 'Authoritative only' servers).

Diagram 3 DNS Resolver (Recursive Server) A caching server will typically have a file which includes the following fragment: To cache or not is a crucial question in the world of DNS.

BIND is regarded as the reference implementation of the DNS specification.

The default BIND behaviour is to cache and this is associated with the recursion parameter (the default is 'recursion yes').

There are many configuration examples which show caching behaviour being defined using a type hint statement in a zone declaration.

Example configuration files for a slave DNS are provided. The definition of a slave server is simply that it gets its zone data via zone transfer, whereas a master gets its zone data from a local file system.

The source of the zone transfer could just as easily be another slave as a master. A DNS Caching Server (frequently called a Resolver) obtains information from another server (a Zone Master) in response to a host query and then saves (caches) the data locally.

There can be any number of slave DNS's for any given zone.

Tags: , ,