Hans du Plooy wrote:-
A lot of our clients run on ADSL connections. ADSL here (in South Africa) have a bandwidth limit of 3gb per month, after which international bandwith is capped (i.e. moved to a 64k line shared by all capped users), rendering it pretty much unusable.
Can't you do DNS queries via your ISPs DNS server? This will keep all your RBL DNS queries off your international bandwidth - obviously if the 3GB limit is for local traffic this doesn't help.
Running DNS locally would of course cut down on bandwidth, regardless (correct
me if I'm wrong). What would be preferable, considering the connection is
used for other things as well: local DNS cache or running bind locally?
Also, it was mentioned that bind needs lots of memory. Is that true for a
dns cache too? How much? We usually have at least a dual Xeon with 1gb RAM
available.
Unless you are setting up zone files and offering DNS resolution then you only need a DNS cache and not a DNS server. djbdns and dnscache are less resource intense than BIND and seem to work well. Definitely having a local DNS cache and pointing all your local systems at it will reduce the amount of bandwidth used for DNS requests - and if you can use your ISP's DNS to resolve names and do the "legwork" so much the better that'll save on more bandwidth.
There is plenty of information about setting up forwarding caches, this link should provide some hints:-
http://cr.yp.to/djbdns/run-cache-x-home.html
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