Diagnosing intermittent "can't find IP" errors

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Tom.G said:
suddenly PF didn't respond.
I've had the same sort of thing. I blamed the PF server but perhaps I was being hasty. At least it wasn't my Bank and PF can always wait without the World ending.
 
You can always check this source for recent attacks. Sometimes, you see spikes on specific days.

https://www.akamai.com/us/en/resources/our-thinking/state-of-the-internet-report/web-attack-visualization.jsp

Here's data from the past week.
Horizontal bar chart of web attack counts by type: SQL Injection 401,608,618; Remote File Inclusion 5,479,856; Cross-Site Scripting 2,796,296; PHP Injection 199,040; Command Injection 19,648.

Bar and line chart titled Attacks per Day, y-axis 0 to 100M, x-axis dates 2019-11-10 to 2019-11-16; orange bars with a blue line over them, the 2019-11-10 bar in yellow.


Bar chart titled Attack Distribution by Country / Source, listing five countries with flags and counts: Russian Federation 103,818,754; United States 75,379,328; Ukraine 62,678,918; Indonesia 14,701,902; Thailand 14,129,358.
 
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It's still happening but good to know there are likely external causes.

At least it wasn't PF, and my bank can always wait without the World ending. :-p
 
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I recently had an intermittent DNS problem. My router has a setting to put a "The internet is down" page up when the internet is down. What it supposed to do is return an ip that the router can serve the error page on.

The IP was 10.0.0.1 or something close.

The problem is that the error page is not there and the all DNS entries gets cached and stuck on the non-existent server address. Ping to an IP address works just fine since the outages were seconds in duration. I found the answer on a 5 year old forum post. Just disable the completely broken "feature".

BoB
 
Most of the time "site cannot be reached" or "unable to connect this site" come because of dns_probe_finished_nxdomain which means because of DNS. There can be many other reason as well
like you can try following steps
  1. Reboot your modem and Computer
  2. Reset chrome flags by resetting to default if your are using chrome
  3. Check your Host file, if the website you are opening is listed under host file you won't be able to connect
  4. flush your DNS
  5. Reset browser
You can read this article for brief troubleshooting steps on how to Fix dns_probe_finished_nxdomain
 
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