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DHCP and routing to the WEB

By Shanghai Sam ·
Dear Sirs,
I'm in the process of changing the TCP/IP from static to DHCP. We have small network with about 20 clients. There are two NT servers and two Linux Servers on the NET. On one of the Linux server (RedHat 7.0) we have two NIC's, where one is connected to a CISCO 1700 that has a fixed IP address. We have been assigned with a small range of IP addresses. This Linux server acts as a firewall where we are masqurading the our internal net from the outside. This is working quite well. I'm now starting to set up the DHCP server, on the Windows NT 4.0 sp6. Every thing seems to be workin quite well, but I'm not able to browse the web any more. I'm able to ping different servers on the outside. The internal network is working working quite well. When using IE 4.0 I'll get this error message on screen:
cannot find'???p:///???p://www. and so on'
I've not setup a DNS / WINS server on the internal network, but has a link to the public DNS as previusly used in the static setup.
Would appreciate inputs how to correct this error in my DHCP setting.

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DHCP and routing to the WEB

by curlergirl In reply to DHCP and routing to the W ...

I'm not familiar with Linux - is this server routing IP traffic between the workstations and the Internet? Have you configured your DHCP server to assign a default gateway address to the workstations? This can be set in the scope or global options- I don't remember the specific option ID but it's the Router option. This should be set so that the workstations are using the internal IP address of the Cisco router as the default gateway. This will ensure that any external IP traffic from the workstations is routed properly. Hope this helps!

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DHCP and routing to the WEB

by Joseph Moore In reply to DHCP and routing to the W ...

It sounds like your DHCP server Scope is not assigning the 003 Router option, that points to your Linux gateway. Put this option in the Scope, then release/renew the IP leases and try again.

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DHCP and routing to the WEB

by NetTek In reply to DHCP and routing to the W ...

Are you saying that you have been assigned a small range of IP addresses by your ISP? If that is the case, you have public addresses and your name resolution is coming from your ISP's DNS servers. You CANNOT use DHCP with DNS. DNS matches fully qualified domain names to static IP addresses (for example, will be listed in the DNS server as linked to . If you dynamically assign IP addresses through DHCP, you are in effect randomly assigning IP addresses that no longer match the name in the public DNS server. You have lost your Internet name resolution.

Pinging does not require name resolution, that is why you get a response, and your internal network is still working because it is using NetBIOS broadcasts for resolution.

You will need to return to static addressing.

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