Use forwarders or not?

[Kevin Darcy]

There are many root servers and they are all big boxes. Ditto for the
gTLD servers like "com", "net", "org", etc. I wouldn't particularly
worry about them getting overloaded. Not your problem :-)

As for using forwarders for performance: if it works, do it! But bear in
mind that the price you pay to *gamble* that the answer to any given
query that your server recurses is in your ISP's cache (or authoritative
data) is an extra name-resolution "hop" for every recursing query.
Sometimes that gamble pays off, sometimes it doesn't. If you generate
some test queries for less popular domain names, for instance, you may
find that forwarding is slower because your ISP's nameservers are less
likely to have the answers cached. Just be aware, then, that while
forwarding may improve your best-case and/or average query times, it may
hurt your worst-case times. That may be an acceptable tradeoff for you.

Of course, if you're using forwarding *only* for performance (as opposed
to using it as a way to deal with some sort of connectivity issue like a
firewall), your mode should be "forward first" rather than "forward
only". This allows you to still operate even if all of your forwarders
are down or unavailable (assuming you still have Internet connectivity).
"Forward first" is the default, by the way, so if you don't have any
forwarding mode explicitly specified, you're already implicitly set to
this mode.


- Kevin
root wrote:

> Hello,
> is it better no to specifiy any ISP-forwarders in the named.conf file
> and use the root servers?
> I noticed that the lookup takes fewer time when doing it with my
> forwarders.
> What I thought is that there must be a lot of traffic caused by all
> these tld lookups on the root servers. What do u think?