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Community Member

Redirecting DNS traffic

We are trying to redirect the DNS query destined to an server to another server at the same time the users would still see the DNS server as the old ip adddress but the switch/router would redirect that traffic to the new DNS server. Is that possible ,If so kindly suggest the same

Thanks

Regards

Anantha Subramanian Natarajan

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Redirecting DNS traffic

Hi Anantha,

According to my understanding to this feature, the router will take the DNS query from the client using the old DNS IP (192.168.1.1) and then it will do a DNS query itself to the new DNS (172.16.1.1), and finally reply to the client with the old DNS IP (192.168.1.1) spoofed giving it the result of the query, i think it might work in your case, please give it a try and feedback us.

HTH,

Mohammed Mahmoud.

10 REPLIES

Re: Redirecting DNS traffic

You can accomplish this with NAT redirection.

Check for "Using NAT During a Network Transition" in the link below.

http://www.cisco.com/warp/public/556/12.html

Community Member

Re: Redirecting DNS traffic

Hi ,

Thanks.

Actually our requirement is to send the DNS query to different ip address(New DNS server) which is in different subnet to the current DNS server and also we don't want to change the DNS server ip address in the clients.So when the client comes to the router/switch where the current DNS server is locating, that router/switch should be able to direct the traffic to the new DNS server.

Is that possible and if so ,How we can achieve this.

Once again thanks for your above message

Regards

Anantha Subramanian Natarajan

Re: Redirecting DNS traffic

Hi Anantha,

I don't think that this is technically applicable, as the DNS query will still be send from the clients to the old DNS IP, and the client will wait for the response from the old DNS with that IP, i think you need the old DNS itself to redirect the DNS requests to the new DNS, other wise you'll need to change the DNS IP defined on the the clients.

HTH,

Mohammed Mahmoud.

Community Member

Re: Redirecting DNS traffic

Hi,

I think, that make sense and thanks.

One more question, can we translate the destination ip address in the IP packet by the router or switch by anyway .

Thanks

Regards

Anantha Subramanian Natarajan

Re: Redirecting DNS traffic

Hi,

Yes you can do nat outside to NAT the destination on the router (translates the destination of the IP packets that are traveling inside to outside).

http://www.cisco.com/warp/public/556/1.html

HTH,

Mohammed Mahmoud.

Community Member

Re: Redirecting DNS traffic

Thanks

Re: Redirecting DNS traffic

Hi there,

I found a feature called DNS spoofing, try to give it a try in your case, i think it might solve your problem as a work around:

ip dns server

ip dns spoofing

ip name-server

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00804455de.html#wp1050022

HTH,

Mohammed Mahmoud.

Community Member

Re: Redirecting DNS traffic

Hi Mohammed ,

This is really gud but I have a question. Say for example my current DNS server ip address is 192.168.1.1 and new server ip address is 172.16.1.1 . The server 192.168.1.1 is connected on switch1/router1. As per my understanding on the above, I would configure in the switch1/router1 the below configs

ip dns server

ip dns spoofing 192.168.1.1

ip name-server 172.16.1.1

Is that right ??

If so, say for example an DNS request for www.cisco.com is comming from a client having ip address 10.1.1.1 towards the old dns server 192.168.1.1 passing through switch1/router1 would be redirected to new DNS server by the above config ? If that is the case, what would the new DNS server would see the packet comming from source address 10.1.1.1 and destination (????).

Kindly let me know

Thanks for all your assisatnce

Regards

Anantha Subramanian Natarajan

Re: Redirecting DNS traffic

Hi Anantha,

According to my understanding to this feature, the router will take the DNS query from the client using the old DNS IP (192.168.1.1) and then it will do a DNS query itself to the new DNS (172.16.1.1), and finally reply to the client with the old DNS IP (192.168.1.1) spoofed giving it the result of the query, i think it might work in your case, please give it a try and feedback us.

HTH,

Mohammed Mahmoud.

Community Member

Re: Redirecting DNS traffic

Hi Mohammed,

Unfortunately, it seems we don't have correct IOS to enable this feature , but really appreciated for your assistance.

Thanking You

Regards

Anantha Subramanian Natarajan

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