DHCP / Local DNS Issue

By corumchris ·
Here's a problem that has been plaguing me for some time and I can't figure out what the problem is or where to start looking.

My network has DHCP served to it via our SonicWall firewall. Our DNS server is running on a Windows 2000 machine.

Sporadically throughout the day random users (all running Windows XP) will suddenly be unable to resolve local server names. Going to their machines, I can see that they have all the appropriate information (IP Address, DNS, Gateway, etc.) However, I have to release their IP address and renew it to fix the problem.

We recently upgraded our SonicWall hardware, however the problem persists. If I "hard-code" an IP address to a machine, the problem goes away.

I'm not sure where the problem lies...with the DHCP server or the DNS Server...or perhaps I'm missing something else?

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All Answers

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Are you sure this is a DNS issue

by Zen37 In reply to DHCP / Local DNS Issue

Are you sure your users are using DNS and not Wins? If their station were to somehow lose their registration within the Wins, could this be causing your problem? I'm not sure how your set up is but local server names in windows are usually resolved by Wins, unless you are using AD.

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Not sure, but not WINS

by corumchris In reply to Are you sure this is a DN ...

To answer your question, no. I'm not positive this is a DNS problem, but we are using AD and Wins is not running on our network.

I'm at a loss as to what it might be...

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does the servers have static addresses?

by CG IT In reply to DHCP / Local DNS Issue

if so, did you create reservations for those addresses in DHCP.
Also did you create options for the services available on the network in DHCP?

Next is did rule out any type of hardware problem. Note: newer NICs have a power saving option that allows the comp to turn off the nic to conserve power. It's possible that's what happens [better to disable that to rule it out as one of the hardware issues that might cause the problem]

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by corumchris In reply to does the servers have sta ...

Yes our servers have static addresses and those IP Address are reserved in DHCP. The DHCP server hands out Addresses based on Hardware address.

This is happening on both newer and older equipment and throughout the company, so I'm leaning towards ruling out a Hardware issue on the client side. Seeing as we just replaced the Firewall (which is the DHCP server) and the problem persists, I'm rulling out a hardware problem there. That being said, I suppose a hardware issue between the two could be causing a problem...could this be a faulty switch or some other piece of equipment in-between the two?

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by CG IT In reply to Yes

could be a switch not forwarding packets.

just for a recap, with network problems, the first step is to rule out any hardware problems first, before going to software.

a switch running store and forward might drop packets. Trunking between switches might cause problems, a faulty cable between uplink ports.....

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Sonic Wall DHCP and Windows 2000

by Josha In reply to DHCP / Local DNS Issue

Sonicwall's DHCP doesn't appear to properly
update windows DNS and clients don't appear
to aid in scavenging stale records. I think
it's related to secure updates, though it
still didn't work when I allowed unsecured updates (not recommended!)

One way to help avoid these problems if you
still want to use sonicwall DHCP is to add
wins to your network. and make sure your
servers DNS address is the only DNS provided
in sonicwall DHCP.
Also make sure your DNS forwarders are up-to-
date(the Ip addresses that your servers goto
when they have to look up outside your
domain.) Under DNS, Forward Zone, and then
your local network zone, right click on your
local network zone and then double check your
Also Make sure your windows DNS is looking to
a Wins server for updates.

It is best to set up a windows DHCP you can
even tell your sonic wall where to get dhcp
if you are using it for vpn.

I can say WINS makes a huge difference when
dealing with this problem on a small network.
Also Redundant DNS and Redundant wins makes
things much faster too.

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