Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.
One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.
can Computer A and Computer B ping all other computers except for A and B respectively ?
What makes computer A and B different than other computers on your network ?
1.Reboot the switch
Several options to try...
2
run the following command (on both A and B) to confirm what their mac address is, this should be unique
start a dos prompt then run 'ipconfig /all'
look for the field PHYSICAL ADDRESS - make a note of the value...
2.
Reboot computer (or prior to a ping from Computer a to b)
login as normal
run a dos command prompt and enter
arp -a
look for the physical address given in option 1 before from the other computer....
ping the other computer A or B, whichever you are not on
run arp-a again and check to see if there is an ARP entry for the other computer.
3.
if this still fails, try another port on your switch, different cabling...