DNS lookup Failure

Hi Everyone

I currently have my domino servers set to perform a dynamic lookup then local hosts lookup. For dynamic however this is failing.

If I perform a lookup from the server at the command line it is fine,

[scc-rs6001] root # nslookup cluster3.eu.messagelabs.com 194.72.6.57

Server: ns3.bt.net

Address: 194.72.6.57

Non-authoritative answer:

Name: cluster3.eu.messagelabs.com

Addresses: 85.158.136.3, 85.158.137.35, 194.106.220.35, 194.106.220.51

      195.245.231.163, 195.245.231.211

The domino log file however gives the below information

Lookup of IP address for host failed

Is there any other specific configuration I need to be aware of

Thanks in advance

Steven