[rhn-users] connexion problem between 2 servers

[FM]

Hello,

My setup : 4 servers with RHEL 3 in the same subnet (in my DMZ)
server1 is my mail server

from server2 : telnet server1 25 : SUCCESS
from server3 : telnet server1 25 : SUCCESS
from server4 : telnet server1 25 : telnet: Unable to connect to remote 
host: No route to host


on server4  arp -e :
gw1.dmz.lexum.pri ether   00:0D:88:EE:96:AC C  bond0
server1.3.16          (incomplete)             bond0

server4 can connect to any server exept to server1 !

I connect all server on HUB just to see if my switches was the prob but 
the prob remains.

Do you already see this kind of weird thing ?

Thanks !

F