kinit ignores kdc in config file on Mac 10.5

[petesea@bigfoot.com]

I have a user with a Mac 10.5 system and it SEEMS like kinit is ignoring 
the kdc entries in the config file.  Instead it APPEARS to do a DNS query 
for the realm and then uses the A records returned and sends the kerberos 
request packets to them.  The result is kinit takes a while and eventually 
fails with:

   Kerberos Login Failed: Cannot contact any KDC for requested realm

I'm quite sure it's reading the config file because I've run kinit via 
dtruss and see it opening the config file and reading it.

I've tried disabling dns lookups in the config file, by setting both 
dns_lookup_kdc and dns_lookup_realm to false, but that doesn't make a 
difference.

There are many other Mac 10.5 users that work fine using exactly the same 
config file, so it must be some setting on this particular Mac, but I'm 
out of ideas where to look.

Thanks for any help.