Slow 'unknown host' response to networked macs from router? (Suddenly!)

Some IOError response tests in my unit test suite suddenly started failing. Have passed several times daily for months, only started failing today - they had a time out of 2 seconds. Chasing this up I found that it was taking over 30 seconds for the IOError to be produced.

We're accessing the web (BT broadband DSL) via a wireless router (Wire2).

Have found out the following:

Traceroute from mac to a nonsense host takes over 30 seconds to respond with 'unknown host'. (Confirmed on 3 machines - All macs running 10.6.2 or 10.6.3)

Traceroute direct from the router's web utility (to nonsense host) returns 'unknown host' in less than a second.

Reboots - including 10 minutes of downtime for everything in the household - have made no difference.

• The problem only started in the last 24 hours.
• Pinging of live servers is normal.
• Web browsing etc is normal.

The problem is specifically only occurring when a host that doesn't exist is开发者_Go百科 looked up.

Anyone got any clues as to why the communication of 'unknown host' out to the network would take a further 30 seconds?

Thanks

Genius friend suggested I change the DNS Server settings in Network settings to some alternative ones provided by my ISP.

Works a charm.