DNS not working but straight ip does???

[doior]

Have a Cisco 2620 connected to a t1 using a Juniper router to the ISP, it cannot pass any traffic that uses DNS. I have checked the DNS settings on the clients and have plugged the info into the router with the correct dns. I can ping all over the Internet and I can ping a host directly connected to the router's ehternet int but it still cannot do this type of traffic. The packets just seem to drop between the cisco and the juniper.

Anyone have any ideas?

Thanks

 

[ChicagoJim]

Are you, or anyone between you and the DNS server, using packet filter that's blocking the DNS server's responses? Statefull firewalls know to allow the datagram to pass through, but a simple packet filter will just drop the server's response. I ran into this problem at a client's site a while back.

 

[tschouten]

Not to mention if you are using NAT at any point in-between the DNS and the local computers you are going to run into some problems.

 

[doior]

Thanks for the feed back. I appreciate it. It turns out the prob was with the ISP. After agonizing all day with working with the ISP they addressed the issue and pointed the finger toward the Cisco router. They made no changes to the config but it started working after the second person got involved in the process. I have configured many routers but never had an issue until this ISP and Juniper was involved. I am still in the dark on what was changed and they would not admit it. I just know they did not make any change to my Cisco router.