Networks

Ask something
Discussion Locked

DNS Problem??????

0 helpful
15 replies

by ccthompson

Closed to new repliesThis discussion is closed. It stays readable, but it takes no new replies.

I recently moved the location of the network to another building. All new equipment ect....

Got Cisco equipment, including IP phones. The consultants I had on this job said that they wanted to change my IP scheme, so they could monitor it remotly from their home office. I had no problem with this.

Just change the DHCP scope and options, changed all the static printers, servers,ect.... Even made new DNS zones. Our voice/data is taken care of through our Adtran from our phone company.

Now the problem I am having is that the internet drops sometimes. Just out of the blue, just drops and two minutes later its back up. At first I thought it was that the router was giving out DHCP address and not replicating with DNS the right way, so I swapped the DHCP addressing back to the server.

Everything seemed better, but a couple days later it came back, I am not getting any unusual errors in event logs, on the switch, router, no where. I cant seem to find this little bug.

So I go back to it maybe being a DNS issue somewhere, since I deleted the old zones and created new, since we had a new address scheme, but I cant seem to find anything anywhere.

Any help is much appreciated!!!

15 replies

by ccthompson

Forgot to mention, our phones and data both work off one "Adtran" unit. So i dont see this being a service provider issue, as our phones continue to work just fine when the internet is down.

by ccthompson

A windows 2003 server is taking care of DNS, a seperate windows 2003 server is taking care of DHCP. The router does handle the DHCP for the phones, as they are on another VLAN.

THanks for the post!

by bfilmfan

Is this an integrated AD zone?

Is the server authoritative for the zone?

Is the zone allowing only secure updates?

Is there a root hint forwarder?

Did you delete the cache.dns file, stop and then restart the DNS service after the DNS zones changed?

Are you using conditional forwarding?

by ccthompson

Integrated AD zone, to all domain controllers (3rd option). THe zone is allowing both secure and non-secure updates.

As for the root hints, there seems to be quite a few of them. I did not delete the cashe file, but i will now. I hope that helps. Thanks again!

by icb's corner

The DNS must resolve queries from computers clients and one of dhcp option is the DNS server.
You can find if your DNS works fine by nslookup utility. Change your DNS server from dhcp option with DNS server of your IP provider and see the computer behaviour. A good ideea is to study the internet traffic with MRTG.

by cg it

It may be DNS but it may not be your DNS that is the problem. Your DNS server answers for your LAN, not for the internet. those queries your DNS can't resolve are fowarded on to the Iternet.

If you have intermittent Internet connection, check to make sure you have more than one of your ISP DNS servers listed for your WAN links.

by cg it

Note: You have to have your ISP's DNS servers listed to gain and have access to the Internet or you'll get a page can not be displayed error message.

by greybeard770

It sounds like DNS is fine - if you can get to it. I think maybe there is one too many DHCP servers in your world. I would check the computers with problems to verify they are for sure getting their DHCP from your Windows network rather than your IP phone VLAN. DHCP servers will respond to any and all requests - that's what they do. Maybe you have a switch that is forwarding DHCP requests to the old address or simply a wrong address. When 'the Internet drops' can you PING out by IP address?

by otl

A thought. Is the routing set up to have VOIP take precedence over Data ? Could steal bandwidth. Much depends on access circuit (T1, E1, DS3, or E3), total number of VOIP phones, number of users, number of users on the phone, settings on the VOIP phones (high bandwidth useage), and Data allocation.

Previously were you using VOIP ? If not then your bandwidth problem (appears to be) could be caused by too small a pipe for what you need.

This discussion is closed to new replies.