2009/01/04

resolving nameservers and forwarders

I made some major changes to my resolving nameserver.
Instead of doing recursive queries for trusted IP addresses, I switched to use the two DNS servers by my serving upstream ISP as forwarders. The added syntax in /var/named/chroot/etc/named.conf is as follows :

options {
directory "/var/named";
forwarders { 1.2.3.4; 2.3.4.5; };
forward only;
};

Do I need to worry about one forwarder fails and the query just got stuck until time-out ? The answer is no. One beauty of Bind 9 is that forwarders are not selected in the order listed or in a cyclic manner. Instead, the nameserver will select which the forwarder to query first based on roundtrip response time. If one forwarder fails, the nameserver will select the remaining working one.

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