Howdy,

So my problem is that the application I support is suddenly taking 12s to return a hostname for a given IP.  Prior to D day, it was taking a more acceptable 1-5s.  I've got the task of convincing IT its their network thats changed as opposed to our application.

I imagine its a fairly typical Win2003 domain (don't have sys admin rights so can't nose about) with Windows running the DNS and DHCP.
Using nslookup tells me that there are no Reverse Lookup zones configured (i.e 2s timeout when querying by IP)
On the server NICs there's no defined WINS server, LMHosts lookup is not enabled and NetBIOS is set to "Default-Use NetBIOS settings from the DHCP server". 
There are no Host file entries on any of the servers.
Server dns and arp caches have been flushed.

The connecting clients have a mixture of both static and dynamic IPs

My questions is, how does reverse lookup even happen in this type of environment anyway?