Why I kept losing network connection?

November 19th, 2003, 7:37 am

I kept losing network connection with my Windows 2003 domain controller server with DNS and DHCP installed. If I reboot the server computer then all my client computers can gain network and Internet access again. There is nothing major that's generated in the event log ethier. Somehow after a couple of hours all the network connection are lost again and I have to reboot the server computer again.

Any help is greatly appreciated! Many thanks in advance!

ljCharlie

November 19th, 2003, 10:04 am

Does the clients DHCP service disable itself?

November 19th, 2003, 10:29 am

Oh! Thank you very much for trying to help me out. I am just about to give up on this problem.

No. I am almost 100% sure the DHCP client service is not disabling itself because all I have to do is restart the server computer and it works again. So I don't think it is the DHCP client service. I believed it has to do with either the DNS or DHCP on the server side, but I don't what exactly it is.

ljCharlie

November 19th, 2003, 11:06 am

Is your server listed as the first IP address in the order of the DNS being handed out to the client PC's. Other than that I would suggest taking a look at your switches also and see what they are doing when the server locks up. You could try and reboot the switches the next time that happens and see if that will unlock everthing for you. Let me know if you need anymore ideas. Also the help on win2003 is pretty good. Enjoy

November 19th, 2003, 11:31 am

Again, thanks for the effort.

Yes, my server is listed as the first with 192.168.0.2 then the rest is 192.168.0.10 and so on.

At first I thought it was the switch so I shut down the switch and restart it again but it's not unlocking all the connections. So at this moment, I'm pretty sure it's not the switch.

ljCharlie

[ATNO/TW]

November 19th, 2003, 11:37 am

Make sure you don't have more than one DHCP server running. If you do, clients get their TCP/IP info from the first DHCP server they find. It may not be the one you want them to get it from. I assume you want it all to be handled by your Server's DHCP. I'm guessing that may be what's screwing up your clients, because they do go out and check periodically. My first thought would be make sure DHCP is turned off in any routers you are using and go from there. When we were playing with this at school last year, we had seven of us running our own Win2K server. As soon as we installed and tested it we always had to turn our DHCP servers off because it would wreak similar havok with the schools network.

November 19th, 2003, 12:43 pm

I only have one DHCP server that's running and my client are getting their IP address correctly. I mean I can see their computer names listed in the DHCP server leases.

ljCharlie

November 19th, 2003, 1:29 pm

Are you using the defaults in the DHCP configuration?

What is the lease time set too?

In the mean time i shall do some investigation.

HAve you checked the event logs on the server??

November 19th, 2003, 2:21 pm

No, I configured the DHCP to to contain conver the ip addresses that I needed. I don't know what is a lease time. How do I find that out? Yes, I checked the event log hundreds of time and no error generated.

ljCharlie

[ATNO/TW]

November 19th, 2003, 2:40 pm

On your DHCP server, right click your scope and go to properties. There you can change your lease time. It's the amount of time before a client's IP allocation is released. Once it is released, then the Client has to request a new one. This is done by a UDP broadcast. You can test this by increasing the lease time to a day or several days. I believe the default with Win2K server is 1 hour. That's a little low in my opinion, and what is happening is that your server is probably getting bombarded with requests to renew.

November 19th, 2003, 9:22 pm

Also to tag along if your renew time is one hour then the PC will start at the half way time of the lease to see if it can keep the same number or not. If it doesn't get a response to that request it waits till three quarters of the lease time has expired and do the same request. If the results are the same where it didn't get a response from the server it will let the lease run out and then do a broadcast looking for a DHCP server to assign it a new address. Enjoy


//also on a side note test out your cat5 connection from the server to the switch and make sure the cable is good. Also try and switch the server to another port on the hub, and see if that changes anything. Just a thought

November 19th, 2003, 10:07 pm

I think you guys are on the right track, and unfortunately I don't have
too many new ideas to add the discussion. I did want to point out
though, that the default lease time on a IP address is 8 days.

This is right out of win2k3 server's help files:

Quote:

When a scope is created, the default lease duration is set to eight days. In most cases, this value is sufficient. However, because lease renewal is an ongoing process that can affect the performance of DHCP clients and your network, it is sometimes useful to change the lease duration. Use the following guidelines to decide how to best modify lease duration settings for improving DHCP performance on your network:

If you have a large number of IP addresses available and configurations that rarely change on your network, increase the lease duration to reduce the frequency of lease renewal queries between clients and the DHCP server. This reduces some network traffic caused by clients renewing their leases.
If you have a limited number of IP addresses available and if client configurations change or clients move often on your network, reduce the lease duration to promote scavenging of old IP addresses by the DHCP server. This increases the rate at which addresses are returned to the available address pool for reassignment to new clients.

It may not be the exact answer to your question, but I would think it's
helpful in terms of understanding what might be happening. MD's & ATNO's
assessment might be the closest to what you need. Check the lease
times, and make sure it's not set to something ridiculously low (1hr) and
set it to a few days. i usually set my scopes to 6 days. It gives a nice
cycle to the workweek, and allows an IP to be retained pretty easily.

As I said, I'm not even sure that's what the problem is myself. I'm running
3 win2k3 servers with no problems like this, so I can only help think a bit.

November 20th, 2003, 6:59 am

Thank you everyone for all your suggestions.

UNFLUX, I think your right on the lease time. When I installed, I didn't change the default lease time at all. I did check all the Address Leases and the expiration date is this 11/28/03, so I'm guessing it's about 8 days.

One other thing, the server IP address is static and should not be listed in the Address Leases, correct? If this is true then that means the server ip address never gets renew, right? And if the server ip address never gets renew then why is the server losing all network connection as well and not just the client if it is a lease time issue. So I'm guessing it's not the lease time. Because once all the network connection have lost, even the server can not ping its own switch, the gateway ip address. If I double click on the Local Area Connection under Network and Dial-up Connection, it still listed as connected...but the server access anything of its own box.

And by the way, I'm not sure if this error in the event log has anything to do with it, but here's what I got in the event log daily even only 4 to 5 hours.

The error event log ID is 29.

Quote:

Source: W32Time
Type: Error
Description: The time provider NtpClient is configured to acquire time from one or more time sources, however none of the sources are currently accessible. No attempt to contact a source will be made for 14 minutes. NtpClient has no source of accurate time.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

As I said above, this error seems to generate every day if not 4-5 hours. I'm not sure if this is relating to the problem or not...but I did use this net time /setsntp:<sntp server ip address> to fix it. But it only lasted for a day or two...if I didn't reboot the server.

Anyway, again, thanks for all your time and effort.

ljCharlie[/quote]

November 20th, 2003, 8:20 am

There is a scope of addresses that are assigned out to clients and then usually there is an exclusive range and in that exclusive range is your static IP's that don't get handed out. So that is where the server address would be, routers, network printers, and other stuff like that. Make sure that you also don't have the server address assigned to another device like a router or printer. That would cause mysterious problems with the network. Enjoy

November 20th, 2003, 8:23 am

I'm quite sure that the server IP address is not assigned to another device. However, I have not checked if those ip addresses are listed in the exclusive section. They should be listed in there, correct? Although I have not checked, I don't think I ever seen those ip addresses listed in that section.

ljCharlie