The company has a network of about 50 machines, 100BASE-TX. No DHCP, all addresses static, of the form 192.168.1.xxx (mask 255.255.255.0). On all Windows XP machines, go to the Internet through a proxy server (192.168.1.1). The problem appeared suddenly
on one of the machines (192.168.1.76). Several times a day it loses connection with the server (does not go ping, don't go packages, etc.). Helped "fix" the network connection. Found that at the time when the connection is lost, the mac address of this machine becomes the same as the server. Accordingly, if you submit a command for clearing the arp cache (arp-d) connection is immediately restored. At the same ipconfig /all shows the correct mac. Virus scan found nothing. Replacing the network card did not help. Assigning mac addresses to static did not help. The program arpwatch
(found in the article ru.wikipedia.org/wiki/ARP-spoofing
) writes something in the spirit of "mac address was changed" (sorry, the exact wording I do not remember, I write from the house).
What could be the reason for such miracles?