07-06-2004 11:57 AM - edited 03-02-2019 04:52 PM
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???
07-06-2004 12:29 PM
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
07-07-2004 08:46 AM
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.
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