Re: [opensuse] Re: Periodic problem resolving URLs?


It is almost trivial to run your own dns caching server. Just a few
clicks in yast. And it really does not use that much ram / cpu. I
have it running on one of my servers with about 20 workstations
pointed at it.

It is currently only using 18megs of ram and about 75megs is paged out
to swap space. And that server has been up for 146 days, so this is
in the fully operational mode.

Assuming you have the ram to work with, if your ISP is unreliable for
dns services you should consider just running your own without even
forwarding requests to your ISP.

In a small business environment like mine, even if the ISP is reliable
you should be running your own local dns primary and backup caching
server. And they should be setup to forward requests that can't
answer locally to the ISPs dns server.

That way if you keep needing to lookup the same domain name
repeatedly, the traffic all stays within your local network. You only
have to ask the ISPs dns server for new info. And by using the
forwarding aspect, you get to leverage the fact the ISPs dns should
have a lot more info in its cache than your server does.

Thus the dns traffic on the internet is cutdown by having a couple
tiers of dns servers like that.

The only bad part is your local dns servers need to be machines that
run 24 hours a day, or at least any time a user might need to be doing
a dns query.

For a home user with a single suse box, this is easy. You just have
named (dns) start as a daemon during startup. And if you have a
reliable ISP dns server, forward unanswered requests to it. If it is
not reliable, then don't forward at all. That means unanswered
requests cause direct queries out to the various domain dns servers.

Note: I guess it is possible an ISP would firewall off outbound dns
requests, but I've never had that problem.

Greg Freemyer
Head of EDD Tape Extraction and Processing team
Litigation Triage Solutions Specialist
Preservation and Forensic processing of Exchange Repositories White Paper -

The Norcross Group
The Intersection of Evidence & Technology
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