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I am working on a Windows 7 (Home Premium) machine, SP1 on a Dell laptop.

Quite recently I started getting "Cannot connect to server error" for only some websites (Gmail, reddit, etc) out of the blue, while I was able to browse other websites easily. The first solution that worked for me was " ipconfig /flushdns" (i.e. flushing DNS). Moment i flushed the DNS the websites were easily accessible.

But now it appears I have to flush DNS more than once everday as I am getting "Cannot connect to server error" on websites. I suspect by flushing DNS i am solving the "symptom" and not the actual ailment. If anyone can throw some light on this, it will be really helpful.

user2979010
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  • Can you provide the output of the command "nslookup gmail.com" before and after flushing the DNS? – krisku May 28 '14 at 07:08
  • `Non-authoritative answer: Name: gmail.com Addresses: 2404:6800:4006:806::1016 74.125.237.213 74.125.237.214` The same before and after flushdns – user2979010 May 28 '14 at 11:49
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    If the results did not change by flushing the DNS cache, I highly doubt your problems were related to that. Next time you have problems accessing a website, lookup the IP address with nslookup and try connecting by IP address instead (just to eliminate DNS problems). You could also try sniffing the network traffic with Wireshark and see what actually happens when you try to browse to a problematic website. – krisku May 28 '14 at 16:36
  • Appreciate your advice, thanks krisku, will do that next time. – user2979010 May 28 '14 at 23:53
  • @krisku I encountered the same problem today. So I did what you suggested. Scenario: cannot connect to Gmail.com (other websites are fine) nslookup gmail.com : 74.125.237.213 Tried accesing that IP via web browser, I was taken to "www.google.com" ....but I could not get to Gmail.com So, I flushed DNS,voila.. i connect to Gmail.com straight away!!... very weird situtaion!! – user2979010 May 29 '14 at 11:53
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    Sounds extremely strange. Do you have other browsers to try? Are you sure you do not have malware in your computer? What about "telnet www.google.com 80" versus "telnet 74.125.237.213 80" in a command prompt? Just trying to identify exactly where the problem lies... – krisku May 30 '14 at 07:56
  • @krisku w.r.t I have SuperAntispyware and malwarebytes, scanning with these returns no detections – user2979010 May 30 '14 at 12:54
  • @krisku running "telnet www.google.com 80" cleared my cmd prompt.. and nothing happened.. so i did ctrl+c to exit.. and i got the below msg `HTTP/1.0 400 Bad Request Content-Length: 54 Content-Type: text/html; charset=UTF-8 Date: Fri, 30 May 2014 12:56:10 GMT Server: GFE/2.0 Error 400 (Bad Request)!!1 Connection to host lost.` – user2979010 May 30 '14 at 12:57
  • @krisku I get the same behaviour for "telnet 74.125.237.213 80"! – user2979010 May 30 '14 at 12:59
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    So you only have problems in your browser? How about switching to another browser? Do you have any proxy settings? Try turning off anything proxy-related (disable proxy autoconfiguration, etc.). Might also be a plugin that causes the problems. – krisku May 30 '14 at 13:54
  • @krisku I have the browser on auto-detect proxy settings. I will switch to another browser when the problem re-appears see what happens – user2979010 May 31 '14 at 00:40
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    Stop using proxy auto-detection, I think that will probably solve your problems. There is really not much use for a proxy nowadays, as most web content is really dynamic anyways. Using a proxy will not give any benefits, unless the proxy is on your side of an extremely slow link.. – krisku Jun 02 '14 at 06:10

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Well the only solution that appears to be working as of now is "clean-installing the OS"!

user2979010
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