forwarders

[Kevin Darcy]

Gerald Waugh wrote:

> Hi,
> I have a subclass 'C' network. I also run my own name servers.
> My ISP has listed two name servers that I may use? (at a significant charge
> / domain - why I do my own)
> Would it be an advantageous to configure my name servers to use my ISP's
> name servers using the "forwarders" or "options" statements?

This depends on how fast you want your queries to be, how reliable/fast your
ISP's nameservers are, the relative speeds of your link to the Internet versus
the speed of their servers to the Internet and to your server(s), how rich
their caches are, whether you frequently have routing problems to the
Internet-at-large, etc. There is no one answer for all situations. Generally,
though, if you have a reasonably fast connection and no routing problems, it
makes more sense to just resolve your own queries over the Internet than to
use someone else's nameserver -- if a given name and associated referral
information doesn't happen to be in the cache of your ISP's nameserver at any
given time, then you may be just *adding* latency by querying it indirectly
through them.

> If so, does my ISP have to do any configuration?

They would need to allow recursion on those servers.

Note that ISP's often segregate their recursive servers, i.e. those used for
resolving queries for their customers' clients, from their non-recursive
servers, i.e. those used to serve up their customer's domains. Don't just
assume that the nameservers used for one purpose are available for the other
purpose. Check with your ISP before trying to use your ISP's nameserver(s)
recursively.


- Kevin