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I'm having a very weird situation on my Window Server 2008 R2 hosts.

In these hosts, we have an ASP.NET Application hosted with IIS 7.0.

The problem is that, eventualy, one of the clients' IP is blocked by the server. In other cases, our own IP is blocked, but this IP is allowed as "full trust" in Windows Firewall.

When this problem occurs, we just ping the blocked client IP from the server, and it is automaticaly unblocked.

I have tested with Microsoft Network Monitor to see if the packets are coming, and they are, but the server does not respond them.

How I can solve that?

share|improve this question
What switching hardware is between the two? – SpacemanSpiff May 15 '12 at 20:27
I don't know which hardware is used, the issue happens in two servers, one of them is a GoDaddy Virtual Server, and other one isn't virtual and is allocated in a hosting company. – Maico Dionisio May 18 '12 at 13:12
up vote 0 down vote accepted

I ran into a similar issue about a year ago, my file server was not recognizing one of the clients. I did the following:

Start->Run-> cmd (enter)-> arp -d * (enter)

Let me know if that helps.

share|improve this answer
The problem happened today, and when I connected with Logmein to try your command, the server already had unblocked my IP address. This is the big problem, it's too hard to diagnose what is happening. – Maico Dionisio May 18 '12 at 13:29
Today the problem happened again, then I started Microsoft Network Monitor and I saw the packets comming from the blocked IP, with no response from the server. I ran arp -d * and the server started to respond. So I scheduled a task to run that command in 5 minutes interval. But why it happens? – Maico Dionisio May 25 '12 at 12:45
To be honest with you I am not sure, but make sure if you are doing any static IPs, you do them via DHCP reservation (if you are using DHCP) that helped me. – George May 25 '12 at 15:25

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