Today at one of my customers I ran into a strange issue after they changed their network subnet from 24 to 23 bits. When troubleshooting this issue we found out that mostly the first ping from a xp/2003 system to the 2008 systems got a reply and afterwards some did some didn't. Especially hosts in the extended part of the subnet were unable to reply. looking at the arp table on both sides showed us something strange on the 2008 systems. the 2008 servers showed us a arp table like below: 192.168.11.4 ......