Handling DNS lookups for local servers

About reducing DNS lookups on remote DNS nameservers

You might be able to reduce the number of DNS lookups performed by remote DNS nameservers by entering local host names and their associated IP addresses in the Hosts File option on the DNS - General page. Configuring the Hosts FIle option enables your NetCache appliance to handle DNS lookups for local servers. As a result, you do not need to configure host names and IP addresses for your local servers on remote DNS nameservers.

When to add entries to the Hosts File option

Typically, you do not need to add entries to the Hosts File option. Add entries to this option only if you have a special requirement to bypass the DNS nameserver.

For example, if you do not want to export DNS information to a DNS nameserver, you can add the host name and IP address to the Hosts File option. If you are setting up this NetCache appliance as a Web accelerator, you could, for example, add entries to this option for the Web servers that the appliance is accelerating. The DNS lookup would then be performed on the NetCache appliance, eliminating the need for a DNS lookup on a remote DNS nameserver.

Note
The DNS caching feature ignores entries input for the Hosts File option. Only DNS data actually fetched from a DNS nameserver is cached to support the DNS caching function.

What NetCache checks first for DNS host name resolution

When NetCache tries to resolve a host name, it checks the local DNS cache first, then checks the entries in the Hosts File option. NetCache sends DNS queries to the remote DNS nameserver only if it cannot resolve the host name from the DNS lookup of the entries in the Hosts File option.