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Resolver Robustness

If you are running a LAN inside a larger network, you definitely should use central name servers if they are available. The advantage of this is that these will develop rich caches, since all queries are forwarded to them. This scheme, however has a drawback: when a fire recently destroyed the backbone cable at our university, no more work was possible on our department's LAN, because the resolver couldn't reach any of the name servers anymore. There was no logging in on X-terminals anymore, no printing, etc.

Although it is not very common for campus backbones to go down in flames, one might want to take precautions against cases like these.

One option is to set up a local name server that resolves hostnames from your local domain, and forwards all queries for other hostnames to the main servers. Of course, this is applicable only if you are running your own domain.

Alternatively, you can maintain a backup host table for your domain or LAN in /etc/hosts. In /etc/host.conf you would then include ``order bind hosts'' to make the resolver fall back to the hosts file if the central name server is down.

Andrew Anderson
Thu Mar 7 23:22:06 EST 1996