AIX 4.3 unreachable

This morning upon arrving at work, 2 of 7 AIX boxes were unreachable, e.g. could not ping successfully and of course could not telnet to the boxes. Rebooting them appears to have resolve the issue. All boxes are in the same switch, same network, etc. I am NOT a networking person so I need some insight as to what may have happened. I find it odd that 2 machines would have this problem at the same time. there are no other issues on these boxes. Any ideas would be greatly appreciated. One person I contacted mentioend ARP tables. Please give me your thoughts.

Thank You

did you try pinging from one of the AIX boxes that was unreachable to 127.0.0.1 to make sure the IP stack was good on the box? also could be ARP table if you have multiple devices running proxy ARP that have routes to those servers. did the interfaces go down on the AIX boxes? was there a link light on the switch showing connectivity? there is multiple reasons this could have happened incliding DOS attack.

Unfortunately the guy who hooked up the switch for the mointor/keyboard doesn't have it hooked up corectly, therefore I couldn't even get on the boxes themselves. I'm afraid I won't know what happened unless it happens again AND they get the switch fixed.

Thanks for your help.