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Question

HELP! My computer has strange DNS problems.

Sep 30, 2018 11:08AM PDT

My Ethernet-connected desktop can resolve only about 30% of the sites that I try to visit. The problem is just with my desktop computer. I don't have any problems If I plug the desktop's Cat-5 cable into my laptop, so it is not a problem with my ISP (AT&T U-verse). My desktop is running Win 10 Pro 64. 10.0.17134

Some of the sites I CAN access include:
google.com, att.com, facebook.com (no sound), wikipedia.com, youtube.com (no sound), CDC.com, NIH.com, mozilla.org.

Some sites I CAN'T access include:
yelp, newegg.com, ebay.com, amazon.com, my Yahoo mail server, download.mozilla.org, and a whole bunch of various other sites.

Note that I CAN access mozilla.org, but I CAN'T access download.mozilla.org

The message I get for about 70% of the sites I try is:
"We can't connect to the server at xxx.xxx.xxx"

These are the things I have tried that have not worked:
1. PING - I can't PING anything, not even my own router or NIC. I get no response when I PING. It just sits there and does nothing. This may be the most important clue to the problem. My other computers can PING anything with no problem.
2. It is not within Firefox or Internet Explorer. They both give identical results or non-results.
3. Multiple reboots don't help.
4. I ran System File Checker and it came back clean.
5. I changed the IPv4 DNS addresses on the Ethernet card to Google's 8.8.8.8 and 8.8.4.4. I also changed the IPv6 DNS addresses to Google's.
6. I did a "Restore Firewall to Default" in Windows Defender. That didn't help.
7. Temporarily turning off Windows Defender Firewall didn't help either.

There is something wrong with this particular computer but I can't figure out what it is.

Discussion is locked

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Clarification Request
Did you try a DNS Flush?
Sep 30, 2018 11:49AM PDT
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Yes
Sep 30, 2018 1:00PM PDT

Yes, I did a DNS flush.
I forgot to add that to the list.

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Clarification Request
OK, now use NSLOOKUP.
Sep 30, 2018 2:10PM PDT
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Hold off for a moment. Check this.
Sep 30, 2018 2:11PM PDT

Be sure your computer's timezone, date and time are correct.

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(NT) They are all correct. Time is within 4 seconds of time.gov.
Sep 30, 2018 2:49PM PDT
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nslookup results are the same
Sep 30, 2018 3:12PM PDT

Amazon.com is a site I can not get to on the desktop.
This is what I get on my working laptop (which doesn't use google for DNS)
---------------------------------------------------
PS C:\WINDOWS\system32> nslookup amazon.com
Server: homeportal
Address: 2602:302:d196:d80::1

Non-authoritative answer:
Name: amazon.com
Addresses: 176.32.103.205
176.32.98.166
205.251.242.103
--------------------------------------------------------------

This is what I get on the non-working desktop (which uses Google for DNS).
--------------------------------------------------------------
PS C:\WINDOWS\system32> nslookup amazon.com
Server: google-public-dns-a.google.com
Address: 2001:4860:4860::8888

Non-authoritative answer:
Name: amazon.com
Addresses: 176.32.98.166
176.32.103.205
205.251.242.103

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well... now everything is working (at least for the moment)
Sep 30, 2018 4:48PM PDT

It's all working now for some unknown reason.
I didn't reboot the computer.
I didn't reboot Firefox.
I didn't do anything.
It just started working.

I will have to repost once it quits working again, I guess.

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I did not note a thing. Here it is and why.
Oct 1, 2018 9:33AM PDT

I did not note trying a browser reset. Folk hate doing that. There is another way and that is to create a new user account in Windows. Make it a local login and admin too. Then test there.

Today's browsers CACHE a lot and I either just reset the browser or try the test in a new account.

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I thought about a browser reset, but...
Oct 1, 2018 10:06AM PDT

I didn't think it would help since I was experiencing the same problems on both Firefox and Internet Explorer.

The list of sites that I could or could not get to were exactly the same on both Firefox and IE.

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Answer
Likely, a connectivity issue was occurring
Oct 1, 2018 9:48AM PDT

Most likely, the DNS problems you were experiencing were related to an issue on the ISP's side. However, it is a good idea to keep an eye out for the same DNS problem in case your router may be the source of it.

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It's possibly an ISP issue, but I'm not so sure about that
Oct 1, 2018 10:02AM PDT

The problems I was having were only on one desktop computer and not on two other computers going through the same router and ISP.

I was testing with two computers side-by-side. One was working the other wasn't.

I keep thinking that the inability to PING on the problem computer is a big clue.
When I would try to PING anything, even my NIC or router, it would just sit there and do nothing---no time out message or anything.