>>>>> "Peter" == Peter Bowyer <peter@???> writes:
Peter> Do you have enough DNS bandwidth for this? Bear in mind that
Peter> queries for the subdomain will hit the main domain servers
Peter> first, so you'll get double traffic for each subdomain query,
It's not double, because the NS records for the subdomain do get
cached and subsequent queries go directly to the subdomain's NSes.
However, it _can_ in practice reach 10% of the query traffic (or more
if you are really unlucky), an insanely high figure primarily caused
by two specific broken versions of BIND (8.3.3 and 8.3.4 iirc). Also,
DNSBLs are (more than regular DNS servers are) often queried by
software which is written by poorly-trained chimps who think they can
re-implement their own recursive resolver without caching, which adds
to the parent-zone query load (though not nearly as much as the BIND
breakage does). In addition, the parent zone has to handle the query
load caused by everyone who typos or misconfigures the DNSBL name (the
number of DNS queries for "n.n.n.n.
http://sbl-xbl.spamhaus.org" alone
is truly terrifying).
--
Andrew, Supernews
http://www.supernews.com
