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New Member

Re-routing of mail server

Im quite new at this so I hope someone can help me with my problem. Currently I have a Cisco 1750 router hooked up to a DMZed Cisco 2900 switch. The switch is connected to 2 devices, an old server (x.x.x.20) and a new mail server (x.x.x.21). Currently all the incoming mail requests are being routed to the old server (x.x.x.20), and i would like to know how would i go about routing incoming mail to the new server (x.x.x.21). Does it have to do with the ACL on the incoming side of the router or does the switch to the redirection of incoming mail to the old server? Please help

New Member

Re: Re-routing of mail server


I beleive you need to check your DNS MX record whether it points to x.x.x.20 or x.x.x.21.

Check also NAT configuration on the router (if it exists) - if .20 is NATed as internal addresses then you need simply change static NAT to point to .21 instead .20.

//Mikhail Galiulin

New Member

Re: Re-routing of mail server

Hi Mikhail,

Thanks for the info i will try that. But could you explain what you mean by the DNS MX record and where do i go to check this?

Also im not really sure how would i go about checking the NAT so could you tell me the command to view NAT information on a Cisco 1750 router? Thanks

New Member
New Member

Re: Re-routing of mail server

Very Simple Method:

Change Old server to X.X.X.21

Change New Server to X.X.X.20

New Member

Re: Re-routing of mail server

Hi CSCO10408957

The reason why i did not do that in the first place is because the old server also serves as a file and database server to PCs on the network. So even if i switched the IPs i have to change the routing of the file/database server for the LAN. But if this solution is easier than the NAT and DNS thing that i am looking up i'll probably try it

Re: Re-routing of mail server

Hi .. basically you need to check which device is doing the redirection for your servers. If the IP addresses of those servers is a private one ( routable only internally) then you must have another device doing the translation so that those servers are reachable from the internet. It is most likely that the translation is being done at your firewall or Internet router. A configuration change pointing to the new server has to be done on it.

If your servers are using a public address ( check the NIC itself) then you would need to modify your access-list accordingly and also change the DNS record for your mailserver (MX record) .. this last point is normally managed by your ISP.

I hope it helsp ... please rate it if it does !!!

New Member

Re: Re-routing of mail server

Hi Fernando,

Thanks for the clarification. They do have internal IP addresses so i would guess the address translation is done at the internet router, which is in my case a Cisco 1750 model. Still fairly new to this, would it be possible to get some help in how I could go about configuring this? I know how to connect to the router and do simple commands like "show running config" etc but im not too sure on how to configure routing of servers etc. Any help would be greatly appreciated

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