We have about 40 file servers in our intranet to distribute software packages. The servers have names like example01, example02 etc. Every name resolves to a single IP-address (A-record) and the IP resolves back to that name (PTR) for every single server.

The thing is, that for a certain file (mypackage.cab) I get different results depending on whether I use:

\\192.0.2.01\fs\pkg\X12345678

or

\\example01.foo\fs\pkg\X12345678

While in one case the file is correct in the other case the file has exactly the right size, but it is all zeros. For a certain combination of client and server I can reproduce this reliably. It doesn´t matter if I download in Windows Explorer, via robocopy or even from Linux with smbclient. It´s always the same, one file corrupt, the other ok.

It happens only for certain combinations of clients and servers, not others. For example:

client01 example01.foo -> OK (192.0.2.01 is also OK)
client01 example02.foo -> broken (but 192.0.2.02 is OK)

client02 example01.foo -> broken (but 192.0.2.01 is OK)
client02 example02.foo -> OK (192.0.2.02 is also OK)

client03 example06.foo -> OK (but 192.0.2.06 is broken)
client03 example07.foo -> OK (192.0.2.07 is also OK)
etc...

In some cases I get the broken file when I use the IP address in other cases when I use the name. For every client the majority of servers is Ok, but from every client I tested I have at least 4 cases of broken files. All this happens only for mypackage.cab (about 5k in size), it never happened for any of the other files in the same directory.

Confused? Certainly I am. Any idea what can cause this or any idea what to try to figure it out is welcome.

Clients are Windows XP. Servers are NetApp filers I don´t have access to. I can (and will) contact the filer team again, but first I have to have an idea what is going on.