Cisco 775 will not bring up ISDN circuit for DNS query

[iarann]

Hi,

We have a cisco 775 that is fully configured and works in most regards. Except that name resolution will not bring up the ISDN call.

If the line is down:
--------------------
If we ping numerical addresses (eg 10.2.1.1) on the remote side, the line pops up & all works fine.

If we ping named addresses (Eg NTSRV) on the remote side, the line stays down.

If the line is up already
-------------------------
Both types of pings work fine.


We entered address mappings into the hosts file and the line works fine ('cause the name has been resolved locally and is therefore using numeric).

The problem is that we require dns to operate so that we can browse the web etc.

We have been through the manuals & the cisco web site and cannot find any reference to this type of problem.

Any help would be appreciated.

John

 

[12122053]

To solve this problem, routers can set up an “ip helper-address,” used to intercept and forward certain types of broadcasts on to a specific device on a separate subnet that knows how to handle the requests.

The IP helper will forward UDP broadcast packets of the following types:

* Trivial File Transfer Protocol (TFTP)

* Domain Name Service (DNS)

* Network Time Service

* NetBIOS Name Server

* NetBIOS Datagram Server

* BootPC and DHCP

* TACACS requests

With an IP helper-address in place, the router forwards packets on to the designated server. When this occurs, the encapsulated packet can be identified as originating from the network segment where the router was. Responses sent back are again intercepted by the router and passed to the workstation just as if the transaction were happening locally.

 

[yizhar]

HI!

I had same problem with a 761 ISDN router.

There are 2 main solutions for this:

1) Configure the router to dial on DNS request, as mentioned above.
I don't remember the exact command.
This might cause unwanted dials on one hand
(like a workstation looking for an internal server using DNS before netbios),
and unwanted delays on the other hand - because of the time to initiate the connection and DNS or other protocols might time-out.

2) Configure an internal DNS server on your network.
This is the recomended solution for my opinion, and I'm using it in several small networks.
Configure a fiction local domain name like "company.local", install DNS service on 1 or better 2 internal servers, configure the domain name and a zone with "company.local", configure internal servers with ISP DNS servers as "Forwarders", configure all servers and clients to use internal DNS servers.

When configured correctly, it works great.

Bye

Yizhar
Yizhar Hurwitz

http://come.to/yizhar

http://teachers.sivan.co.il/yizhar

 

[iarann]

Thanks for the directions.

As it turns out it was actually a bug in that patricular version of the OS. We doownloaded the latest ( for Euro ISDN) and it works like a dream.


John