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Solved! Something to think about. Website unreachable after router reboot ! Issue resolved though!

iamgenius

Senior member
Jun 6, 2008
622
40
91
So my home network consists of about 25+ devices connected both via wifi and wires. My router (Netgear Nighthawk R7000 ) acts up from time to time so I decided to reboot it. It rebooted and all is fine except that my wife machine (wired directly to the router) refused to connect to one website. It says it is unreachable. The website is accessible from all other machines however. I can't ping the website from the command prompt in this specific machine, however I can ping its ip address. When I fired my VPN service I was able to get into the website. Turned it off, no go! I checked the hosts file, nothing strange there. I thought this is too weird, that's why I'm putting in here.

Anyways, I decided to reboot the router again. Waited few minutes, checked again with the machine in question and the problem is gone. What gives!
 
Last edited:

VirtualLarry

No Lifer
Aug 25, 2001
51,645
6,725
126
The Microsoft caching DNS resolver component on Windows, does what is called "negative caching". If a DNS name is unresolvable from upstream, then, for a few minutes, the MS resolver caches a "negative" result, and will result in "site not found" errors.

Rebooting the upstream router, will cause the MS resolver on the PC, to not "see" the site, (since you just rebooted the PC's upstream resolver), and likely cached a negative or "unreachable" result, for a few minutes.

At least, that's my guess.

It can happen if your ISP's upstream DNS "burps" or becomes briefly unreachable, sometimes Windows will cache a negative ("NXDOMAIN") result for the site that you were trying to reach for a few minutes as well.

Google for "dnscache /flush" instructions.
 
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VirtualLarry

No Lifer
Aug 25, 2001
51,645
6,725
126
The Microsoft caching DNS resolver component on Windows, does what is called "negative caching". If a DNS name is unresolvable from upstream, then, for a few minutes, the MS resolver caches a "negative" result, and will result in "site not found" errors.

Rebooting the upstream router, will cause the MS resolver on the PC, to not "see" the site, (since you just rebooted the PC's upstream resolver), and likely cached a negative or "unreachable" result, for a few minutes.

At least, that's my guess.

It can happen if your ISP's upstream DNS "burps" or becomes briefly unreachable, sometimes Windows will cache a negative ("NXDOMAIN") result for the site that you were trying to reach for a few minutes as well.

Google for "dnscache /flush" instructions.
 
  • Like
Reactions: iamgenius

iamgenius

Senior member
Jun 6, 2008
622
40
91
The Microsoft caching DNS resolver component on Windows, does what is called "negative caching". If a DNS name is unresolvable from upstream, then, for a few minutes, the MS resolver caches a "negative" result, and will result in "site not found" errors.

Rebooting the upstream router, will cause the MS resolver on the PC, to not "see" the site, (since you just rebooted the PC's upstream resolver), and likely cached a negative or "unreachable" result, for a few minutes.

At least, that's my guess.

It can happen if your ISP's upstream DNS "burps" or becomes briefly unreachable, sometimes Windows will cache a negative ("NXDOMAIN") result for the site that you were trying to reach for a few minutes as well.

Google for "dnscache /flush" instructions.
Very interesting. It now makes sense. Thanks Larry.
 

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