I have come across a Windows 7 PC that is unable to telnet to an IP address on any port. The Windows Firewall is disabled and it has no third party firewall installed. We are seeing the following behaviour: It is able to telnet using a hostname but NOT the using the IP address the hostname resolves to. We have tried several different servers and we are able to telnet to them from different computers. Telnet to hostname on any listening port works. Pinging the hostname resolves it to the correct IP. Telnet to that IP address on the same port(s) does not work. This eliminates DNS. I have checked the servers and they are listening on the correct ports and bound to the IP addresses I am trying. Some of them only have one IP address anyway. Other computers are able to telnet using both hostname and IP. The computer in question has this problem with any server, be it directly attached to the local LAN or a remote network. Is there any known bug in Windows 7 that may cause this? Mike

Hi, Please try to boot into Safe Mode with network to check how it works. Meanwhile, I would like to suggest you reset TCP/IP in privileged command manually: netsh int ip reset resetlog.txt Also, clear the DNS cache: ipconfig /flushdns If this issue persists, try to reinstall the Telnet component in Windows feature. Hope it helps. Alex ZhaoPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, I am just writing to check the status of this thread. Was the information provided in previous reply helpful to you? Do you have any further questions or concerns? Please feel free to let us know. Alex Zhao TechNet Subscriber Support in forum. If you have any feedback on our support, please contact tngfb@microsoft.comPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Alex, Thank you for your reply. I will give the suggestions another go. I had already tried these before, including flushing the DNS cache even though I don't believe it can be DNS related. Regards, Mike

Hi, Thanks for update. Currently, we can try to use process monitor to see if there is any clue on this issue: Troubleshooting with Process Monitor Meanwhile, please capture the network traffic with network monitor,and post the output in forum for analyzing: Microsoft Network Monitor 3.4 Alex Zhao TechNet Subscriber Support in forum. If you have any feedback on our support, please contact tngfb@microsoft.comPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, How are things going? If you could update us at your earliest convenience that would be wonderful. Regards, Alex Zhao TechNet Subscriber Support in forum If you have any feedback on our support, please contact tnmff@microsoft.com.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, How are things going? I have not heard back from you in a few days and wanted to check on the status of the problem. Please let me know how the troubleshooting steps turned out. Regards, Alex Zhao TechNet Subscriber Support in forum If you have any feedback on our support, please contact tnmff@microsoft.com.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hello, If you can telnet using the hostname but not the IP address check that the hostname resolves to the same IP address. By hostname I assume you mean the Netbios Name, not a FQDN. If this is so, check your hosts files and WINS entries (if you are using WINS) for static entries that may be pointing the hostname to a completely different IP making the problem even harder to solve. Also, check outbound firewall rules on the PC and/or packet filter rules on the router that may be blocking access to that particular IP address from that host.Miguel Fra / Falcon IT Services Computer & Network Support, Miami, FL Visit our Knowledgebase and Support Sharepoint Site

Hi, As this thread has been quiet for a while, we assume that the issue has been resolved. At this time, we will mark it as ‘Answered’ as the previous steps should be helpful for many similar scenarios. If the issue still persists, please feel free to reply this post directly so we will be notified to follow it up. You can also choose to unmark the answer as you wish. BTW, we’d love to hear your feedback about the solution. By sharing your experience you can help other community members facing similar problems. Thanks for your understanding and efforts. Regards, Alex Zhao TechNet Subscriber Support in forum If you have any feedback on our support, please contact tnmff@microsoft.com.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.