【previously, this article described many errors. i update it 20100815 】
Recently, I am working for a customer on upgrading Exchange Server 2003 to Exchange 2010. Before that, the customer plan to move all servers to a new datacenter. So first they to some test like IP change process.
let me demonstrate:
ISA internal IP 10.1.1.253 GW 10.1.1.254, External IP 202.106.x.x
Exchange IP 10.1.1.80 GW 10.1.1.254
IP change process:
ISA internal IP 192.168.1.253 GW 192.168.1.254, external IP 202.106.x.x
Exchange IP 192.168.1.80 GW 192.168.1.254
ISA internal IP 192.168.1.1 GW 192.168.1.254, external IP 192.168.2.250 NAT 202.106.x.x
Exchange IP 192.168.10.80 GW 192.168.10.254
Now Exchange is not working.
nslookup 126.96.36.199,failed. even on DC shows DNS query out of time.
Because there is no DNS server in DMZ and DC can not forward DNS query to external. So ask Network team release DC dns query (port 53)to externla. All messages in queue sent out.
2-message send out to external. but can not receive messages.
from external telnet 202.106.x.x port 25 , no respond.
From internal telnet 192.168.10.80 port 25 ,respond.
From ISA telent 192.168.2.250 is no respond.
now I was a little confused on why isa do not respond. the only difference is the external IP. I am get a response from Network team that all tracffic from 202.106.x.x will forward to 192.168.2.250. And all tracffic from 192.168.2.250 will forward to 202.106.x.x
after some discover effort, I was thinked on the internal IP set settings on ISA. because intenal ip and external ip is almost in a big subnet, I think isa admin may miss the change process. So check it, bingo!
remove the external ip. then test again, still failed. I am crazy! The best and basci sence is reboot the isa server. Ok, it works. hooray!…..
but wait! I do not see the banner. It is not right. But it show it is still a configuration error on ISA.
the reson is that i create a client usage rule of SMTP, it is not the SMTP server publish rule. after change back to the old rule, everything works.
Total working time: 4 Hours. From 8:30 to 12:30.