Any networking gurus out there?

I'm having a problem connecting to the internet via a couple of Windows 2000 Professional clients. For the past two days, these machines have lost their connections at about the same time of the day. Yesterday, service resumed after a couple of hours. Today, nada.

We have about 24 clients in our business connecting to the internet using DSL, a bridge, and a 4 port Cayman router. None of the other machines are affected. These 2 clients are unique in that they are the only ones using Windows 2000 and are connected directly to the router rather than through the bridge.

In the mornings we log on these clients, connect to a Unix based mainframe through a serial port via a terminal program (Reflections), and load a couple of web based applications. I keep a browser (IE 5.5) window open to access other sites through the course of the day. The strange thing is that when we cannot access the internet via IE, the 2 web based applications we load first thing in the morning continue to function. Any new browser activity is greeted with a DNS error.

Although I can't browse the internet, I can view all the other clients via Network Neighborhood and successfully ping other clients on the intranet.

Well...the internet just came back up on these machines, but it was down for 4 hours and I would sure like to figure out what is causing this problem. Any suggestions or comments would be appreciated.

By the way, I've tried simple things like rebooting on one of the machines. I didn't want to reboot the other because we would lose all access to our web based utilities and one operational machine is better than none. I'm slowly trying to educate myself on Windows 2000 networking, but it's difficult to research this problem and perform my other duties. After some study, I thought it might be a problem with DNS caching, but an "ipconfig /flushdns" did not resolve the problem. I've also tried swapping connections with other clients that are not experiencing problems, no difference. It seems to be exclusive to Windows 2000. Has anyone experienced this problem?

This may be impossible to diagnose over the web. Try some of these things.

Pick a web site, any web site, determine its IP address by pinging the website name, create a host file on the W2K machine for that web site. When you cannot access the web try that specific web site with the browser. If it loads then your DNS provider is having problems. If it does not respond then you need to look internally first. I am a Cisco person and don't know anything about Cayman routers, but if it were me I would buy a small 4 port switch then connect the router to one port and the two PC's to two other ports. Check your network cards and cables to make sure they are OK. If you get too much errors/collisions/noise this could be causing your problem.

Do you have any type of Access Control Lists set up or other types of packet filtering, usage policy, or security in place that could be causing this?

Do you know for sure that you actually have internet connectitivy when this happens? Is any other type of traffic going across your DSL connection?

I'd thought of pinging a website, but wasn't sure how to determine the IP address. Your suggestion led me to ping www.freerepublic.com and lo and behold it returned an IP address. The next time it goes down, I will attempt to ping FR and see what happens.

I've got 3 clients in my department, only the 2 WIN2000 machines are experiencing problems. I tried swapping the cables at the router and bridge between one of the WIN2000 clients and the WIN98 client in my department, no change.

As you may have determined, I am very new to WIN2000 and am very limited in my experience with networking. Unfortunately, I am the go to guy here at our business. A call to our ISP was greeted with an automated system that was really no help at all, pretty much what I expected.

The installation of my home network and the network here went off without a hitch, negating the need for me to really familiarize myself with the intricasies involved in maintaining the systems.

I did find some entries in the event log that I believe coincide with my problems. They state:

"The browser has forced an election on network \device\Nbf_{device number} because a master browser was stopped"

I am trying to research these entries(Event ID 8033), but most of the hits I receive on searching are pretty high tech and would take some time for me to understand.

As far as access control, packet filtering, usage policy, or security are concerned, the machines are pretty much in the same state they were in "out of the box". To my knowledge, other than user ID's, no other restrictions have been intituted. The problems occur with a standard user log in or when I'm logged in as an admin.

The problem is exclusive to the 2 WIN2000 machines, no other clients in the business are experiencing any problems. They are all on WIN9x.

Thanks for taking the time to respond and offering suggestions. I will try to ping a website IP when the error returns and will report back. Thanks again.

I will attempt to answer your questions. The W2K machines are set to obtain an ip address automatically and to obtain DNS server address automatically. This information is from the DNS tab of TCP/IP advanced properties of Network properties. I was under the impression that the Cayman DSL modem/router acted as a DNS server as it dispences the IP addresses to the clients. The IP address of the router is 192.168.1.254 and one of the W2K's is 192.168.1.4. I assume that this is typical of small intranets. I'll show my ignorance of the subject matter by admitting that I'm not familiar with host files.

If you consider this a lost cause, I will certainly understand, but I've answered your questions to the best of my ability. The systems continue to operate today, so perhaps it was congestion or some such issue. I just found it strange and too coincidental that only the W2K machines were affected.

Thanks again for taking the time to respond.

DHCP is the protocol that dispenses IP addresses while DNS resolves hostnames into IP addresses.

If your WIN9x machines continue to work fine but the W2K does not then it does not seem that your router or DNS service is this problem.

Let's go back to the PC's themselves. Turn off any power management features within W2K and within the BIOS of the PC. Power management causes all kinds of weird problems. Are you using built in network adapters or did you put adapters in a slot. Do you have the latest drivers for these adapters. What speed are the adapters and what speed are the ports on the router? If gigabit or fast ethernet try to take one of the connections back down to 10Mb and see if you continue to have the problem on that machine. Once again I never direct connect my PC's to a router but put a hub or switch in between them (switch is better).

It may be Monday before I can check back.

Try pinging your DNS servers, by the numeric (IP) address. I don't have W2K, so can't guide you exactly to the right spot. On my WinXP, its in:

My Computer
Control Panel
Network Connections
Right Click for Properties on the Local Area Connection
Select Internet Protocol (TCP/IP)
Click on Properties
Preferred and Alternate DNS server IP addresses

If you can ping other sites (like freerepublic.com) by number, but can't ping your DNS servers by number, then they went down. Contact your ISP or whomever runs them. All but the most incompetent ISP will be well aware of any such DNS server crash. You need at least one DNS server to translate the human readable URLS (such as freerepublic.com) into numeric IP addresses (such as 209.157.64.200).

If you can ping at least one of your two DNS servers (most folks have two) by numeric IP address, but not ping any site by name, then the hardware system that runs the DNS server software is up, but for some reason (difficult to debug from here) you aren't able to use that service, perhaps because that DNS server software isn't running on that hardware system like it should be.

Thanks for responding. The W2K boxes are set to obtain DNS servers automatically. I'll check the ISP's web site to see if they have a list of IP numbers for the DNS servers. Is there another way to determine the DNS server IP addresses without contacting the ISP?

I do believe that the problem lies with the W2K machine's ability to contact the DNS servers. All the other clients here, they are all on Win9x, are operating without any loss of service. When the W2K machine's internet access goes down, you receive nothing but a DNS error page when using URLS, but by typing FR's IP address in the address bar, the page comes up.

I'm away from the machines until Monday. I will spend what time I can researching my ISP's DNS server addresses and W2K's handling of DNS. Unfortunately, the problem is intermittent, occurs at random times, and resolves itself after a period of anywhere from 1 to 4 hours.

To add even more difficulty to the situation, the machines are in almost constant use during business hours limiting the time I can spend trying to diagnose the situation. The fact that I have only an elementary understanding of networking terminology and protocols adds to the level of frustration. </whine

Thanks again for responding.

It looks like I can determine the DNS server IP addresses by typing "ipconfig /all" at a command prompt. I'll try this with the internet working and with the service down to try to determine if it's a problem with my ISP's servers or with the W2K machines's handling of DNS.

I'm really leaning towards a fault with W2K's DNS handling because it seems like the Win9x clients would also experience DNS errors if it was the ISP's servers, no?

You need to talk to your ISP. I assume they provided the router with the DSL service. It is very possible that the W2K machines are working correctly to a point. Your ISP'S DNS server may be rejecting the DNS queries from your W2K machines or your router may be refusing to pass the queries out. I know that some of the big guys (AT&T, Sprint, etc) will start blocking DNS queries from some customers if they are not accepting time outs. Have your tech support look at your router and their system logs to see if they can determine anything.

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