DNS caching and optimization

Caching-only DNS servers are not authoritative for any domains , but rather just cache results from queries asked of them by clients . Just like a proxy servers that caches popular web pages for a certain time , DNS addresses are cached until their time to live (TTL ) expires . THis will reduce the amount of DNS traffic on your Internet connection , as the DNS cache may be able to satisfy many of the queries locally . Of course , client computers must be configure dto use the caching - only name server as their DNS server . When all clients use this server as their primary DNS server , it will quickly populate a cache of IP addresses to names , so that previously requiested names can quickly be resolved . DNS servers that are uthroitative for a domain also act as cache name - address mappings of hosts resolved by them .

Bind (named)
Blind is the de facto standard program used for name service on Internet . When Blind is installed and running , it will act as a caching server ( no urther configuratuon is necessary ) . Bind can be installed from a package such as a Debian package or an RPM . Instaling from a package is usually the easiest method . In Debian , type

apt-get install bind 9

In addition to running a cache , Bind can also host authroitative zones , act as a slave to authriitative zones , implement split horizon , and just about every-thing else that is possible with DNS .