DNS cache on a WIN98 machine?

[Ace69]

Is there a DNS cache of some sort on a WIN98 machine? The reason that I am asking is because we have some customers that are having problems resolving names. Is it the lmhosts file? We have noticed that if someone has our DNS servers input in their TCP/IP settings they will not work for some reason. However, if we input another DNS, it works! The odd thing is after we switch out the DNS numbers to the other one and then switch back ours again, it works! Some other guys are thinking that the DNS cache on their system is corrupted. My question is, where is this "DNS cache" because I have never heard of such a thing on a workstation?