Hostname lookup failed?

[Ben Elliston]

I just got a note from amcheck about a problem with one of my client
workstations:

Amanda Backup Client Hosts Check
--------------------------------
ERROR: metro: [addr 203.24.38.228: hostname lookup failed]
Client check: 5 hosts checked in 1.692 seconds, 1 problem found

This is nonsense -- I can ping the host, so my resolver is not broken.
What else can cause this?

Thanks, Ben