A friend of mine who works at a school in the bay is having some terrible network problems.

A week ago, his network started running slow for varying random periods. It would run normally for a while, then slow for 20 mins. The problem seemed to increase, with the more users that were logged on. The work stations will freeze, but are fine (after 2 secs) if the LAN plug is removed. It takes 5 mins now for users to log on. This does not seem to be a hardware related fault whatsoever, the server and switches are tested good. The Server is running 2003, the PC's XP pro, security is Mcaffy. I have found some info on net re DoS attack venerabilities on the prog 'Synchroneyes', which is currently being looked into.

Any ideas?

Sounds like it could be a DNS issue. Get your friend to check the Windows Event Viewer on the Server - he should have a separate area in the Event Viewer for listings of DNS Server warnings and errors. If that area is completely empty, he will have to go into the DNS Server management area and switch logging on.

Let us know if that helps

Thanks, will do tomorrow.

He told me today that he thought he had cracked it. He changed the main switch, and it worked perfectly for about half an hour....then it didn't!