Failed to resolve DNS records behind router..

[onpage3cisco]

Hi,

I have created a network topology by using GNS3, I have created a DNS server behind router 3600.

All other work stations are also behind diffrent routers, with diffrent external addresses.

No issues to ping external ip address of the DNS router from any where in the network, I'm pinging from the work stations and setup the correct DNS IP address.

The DNS server is well setup, no issues with nslookup. The router has internal network address.

The problem , I think I'm missing something in my router configuration (NAT, Port forwarding..) None of the worstations is doing resolve to

the dns records on the DNS server.

Any ideas ?

Thanks In Advanced.

[John Blakley]

It's going to be hard to tell you without seeing the config, but generally speaking it's usually a case of having an acl on the wan interface that doesn't allow the request back in. First thing I would do is remove anything security related off of the interface and see if it works before putting on acls, cbac, etc. Otherwise, post your config and we can help you further...

HTH,

John

[onpage3cisco]

Hi,

Thanks for the quick reply.

I have attached my config router settings behind the DNS server (10.10.2.10)

!

version 12.4

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

!

hostname COLO_2

!

boot-start-marker

boot-end-marker

!

no logging console

enable secret 5 $1$wPYg$AyyigqiQptspKno6pqKvC0

!

no aaa new-model

memory-size iomem 5

!

!

ip cef

ip host CORE 172.16.0.2

ip host COLO_1 172.16.1.2

ip host COLO_2 172.16.2.2

ip host ISP 172.16.0.1

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

interface Tunnel0

description = GRE Tunnel To CORE =

ip address 192.168.200.2 255.255.255.0

tunnel source 172.16.2.2

tunnel destination 172.16.0.2

!

interface Serial0/0

ip address 172.16.2.2 255.255.255.252

serial restart-delay 0

!

interface Serial0/1

no ip address

shutdown

serial restart-delay 0

!

interface Serial0/2

no ip address

shutdown

serial restart-delay 0

!

interface Serial0/3

no ip address

shutdown

serial restart-delay 0

!

interface Ethernet1/0

description = To COLO_2 LAN =

ip address 10.10.2.1 255.255.255.0

half-duplex

!

interface Ethernet1/1

no ip address

shutdown

half-duplex

!

interface Ethernet1/2

no ip address

shutdown

half-duplex

!

interface Ethernet1/3

no ip address

shutdown

half-duplex

!

router eigrp 100

network 10.0.0.0

network 192.168.200.0

no auto-summary

!

ip http server

no ip http secure-server

ip route 0.0.0.0 0.0.0.0 172.16.2.1

!

!

!

!

!

!

control-plane

!

!

!

!

!

!

!

!

!

!

line con 0

line aux 0

line vty 0 4

password cisco

login

line vty 5 15

password cisco

login

!

!

end