dns forwarding

[grunky]

I'm working on replacing a customer router w/ a 1605. The previous router acted as a dns-caching server, something that a 1605 does not do.

In order for this router to be a drop in replacement dns queries going to the internal address need to be passed along to the external dns server.

I've tried the below configuration w/o success.

inter eth0

ip address <public ip>

ip nat outside

!

inter eth1

ip address 192.168.0.1 255.255.255.0

ip nat inside

!

ip nat outside source static udp <public_ip_eth0> 53 <ip of dns server> 53 ext

ip nat inside source list internal interface Ethernet0 overload

!

ip access-list standard internal

permit 192.168.0.0 0.0.0.255

I realize repointing dns entries on the dhcp server would be the easiest and quickest solution. This is kinda out of the question.

Any suggestions???

[Georg Pauwen]

Hello,

I have not tested if this works, but you might want to try the global command:

ip forward-protocol udp domain

and the interface command:

ip helper-address x.x.x.x (where x.x.x.x is the IP address of your DNS server).

Regards,

Georg

[grunky]

Tried that.. Didn't work.. I put the helper address on the internal interface and pointed it to the dns server.

I tried a dns query on the ip of the router and it returned nothing. From my understanding the helper-address forwards udp broadcasts - ie for dhcp/bootp a dns query is a udp unicast.

Since a number of people have suggest the same I might be doing something wrong. I'd suggest you try that in your own environment as it didn't work for me.

Thanks for the suggestion though.