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Losing internet connections

I have several users who are logged into Active directory Windows server 2003 std. the computers run windows xp pro. They are logged in for about 7 hours a day when all of a sudden, around 2 pm, they lose internet connection. A reboot fixes it, but what could be the cause? and solution? it does not affect everyone, but consistantly affects about 20% of network users. Does anyone have any ideas? I have rebooted the firewall. No changes have been made to AD or the users.
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geriatricgeek
Asked:
geriatricgeek
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7 Solutions
 
ks_adminCommented:
Could be that DHCP client addresses are expiring?

When one of them loses Internet, can you verify what the IP address is..  and start seeing what you can can't communicate with.  Try pinging the default gateway, try pinging your DNS server(s) and various websites.  Once you know this, you can narrow it down better.

ks_admin
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geriatricgeekAuthor Commented:
The DNS server is also the domain controller. that is up all day as I look at the screen all day. the IP addresses are hard coded which eliminates the DHCP lease. The gateway is the same as the firewall. The machine I am on has the same gateway and I have the internet up all day and do not lose it. I am narrowing it down to about 8 machines. Although today, one of the 8 did not lose internet access.
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ddiazpCommented:
Check your DHCP pool, make sure you have available IPs.
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geriatricgeekAuthor Commented:
I have available IPs for DHCP. these machines have assigned IPs though.
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ks_adminCommented:
When you say they lose internet, you mean they can't ping the gateway?  Or they can ping the gateway, but not past it?

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geriatricgeekAuthor Commented:
they can ping the gateway. but don't get past it.
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ddiazpCommented:
are you running routing protocols or everything is static routes? Are you using VLANs?
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geriatricgeekAuthor Commented:
everything is TCP/IP. everyone is on one segment of the network. Static routes. VLANS are used somewhat. This problem actually started about a week or two ago. What I'm finding is consistant-- same 8 machines, same bat time, and a reboot fixes it until 2 pm the next day. No changes to the routes were done, no changes to the firewall. Same DCs. no upgrades. although Windows updates did go through a few days before this problems surfaced. I raised the question of windows updates and that got shot down. I can't find anything that would cause this.
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ddiazpCommented:
Do they all connect to the same switch through the patch panel? Anything these guys have in common? (same department?)

Have you tried plugging in a working device on any of their switchports when the problem occurs?
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geriatricgeekAuthor Commented:
I'm trying to brainstorm what is common about the users and machines that lose the connection. There are several departments involved and 2 switches involved. In one case, there are 3 people in adjacent cubicles, and only 2 lose the connection, 1 does not. similar computers in this case. All running xp pro. They only lose internet connection. they can still get network resources, printers, e-mail etc.
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ks_adminCommented:
If they can't get past the default gateway, can you tell us what those IP adresses are?  I think we're missing some basic information here..  subnets, VLAN gateways, routing types, etc..  anything that would help us narrow it down.

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geriatricgeekAuthor Commented:
using CIDR: and static IPs
example machine: 192.168.30.140/16
gateway: 192.168.10.23
the switches are all in the default primary Vlan. I'm not sure what you mean by routing types. It is a one location LAN and there are no routers other than the DC and the gateway which also is the firewall appliance.
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ks_adminCommented:
If you can't ping 2.2.2.2 from one of the failing machines, then look at the routing table.  If there's no static route defined on the workstation (why would there be for 2.2.2.2) then it goes to the default gateway.  If you can reach the default gateway, but not anything past it, you need to look at that device and figure out why it's not forwarding the traffic.  If the logs show that it is indeed forwarding the traffic, and it's not coming back, then you need to look further down the line.
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ddiazpCommented:
So you have a 192.168.0.0/16 network spanning on two switches, with a router on 192.168.10.23 facing the internet, DHCP assisning correct dhcp options and everyone's default gateway is set to 192.168.10.23?

Is your network using etherchannel between the switches? are there redundant links between the switches that may not be configured correctly on spanning-tree?

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geriatricgeekAuthor Commented:
question 1 is yes. although the computers have static IPs. question 2 is no to part one. It is an HP switch. part 2 is probably no also. There have been no recent changes to the switches or network config. It has been in place for months (at least) and this issue has only been happening for 2 weeks.
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ddiazpCommented:
Do you use IAS or any other tool that can be configured to block access at specific times? on the firewall, router or server? Is it alwasy 2 o'clock that it happens?
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geriatricgeekAuthor Commented:
IAS is now only used for VPN access. the wireless access goes through packet fence. The firewall has been looked at by the network security person and have sworn up and down that nothing is being blocked. It only happens to the same 8 people. Narrowing down the time put it at between 2 and 2:10 today. The main quesiton I have been asking myself is what happens at 2 PM? nothing stands out.
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ddiazpCommented:
Is there a common AD group that all these 8 users happen to belong to?

Regarding the AD structure, are the user accounts on a common OU or container?
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ddiazpCommented:
Do you have a trendmicro server by any chance?
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geriatricgeekAuthor Commented:
we have trend micro as AV and firewalls on the individual computers. yes. I'm looking into common groups. again, no consistency. it involves sales, accounting, engineering, and factory personell. an inconsistent mix. yet one salesperson and managers have not said they lost connections.
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ddiazpCommented:
Do you have a trendmicro server updating clients on these machines?

Does the trendmicro server get affected with internet connectivity?
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geriatricgeekAuthor Commented:
After 2 weeks of frustration, it looks like the culprit is a test Kace Box that is being tested. I shut it down, waited for 2:09 and nothing happened. the connections held. thanks for all your efforts and input. It was tough figuring it out.
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