Question for Tech Gurus : DNS Resolution Failure

[2MuchMark]

Greetings earthlings,

I was wondering if someone could help me out with a puzzle. When my GF connects her computer to our home network, our modem's error logs shows lots of errors that look like this

2018-09-27 06:48:52 ERR DNS DNS name resolution failure (isatap.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (teredo.ipv6.microsoft.com)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (wpad.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (wpad.corp.YYYY1111.org)
2018-09-27 06:48:53 ERR DNS DNS name resolution failure (wpad.corp.YYYY1111.org)
2018-09-27 06:48:55 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:55 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:55 ERR DNS DNS name resolution failure (casagsep1.corp.YYYY1111.org)
2018-09-27 06:48:55 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:55 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:56 ERR DNS DNS name resolution failure (_ldap._tcp.SRASv2-Oakhill._sites.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:56 ERR DNS DNS name resolution failure (_ldap._tcp.dc._msdcs.corp.YYYY1111.org)
2018-09-27 06:48:57 ERR DNS DNS name resolution failure (XXXX1111.corp.YYYY1111.org)

(I changed the domain listed above for privacy as she's not in adult).

Look at the time stamps - Her computer seems to be generating about 2 errors per second. The error log becomes so large after a while that it actually crashes the modem.

Any suggestions?

[k0nr4d]

Try disabling IPV6 on your router

[2MuchMark]

Originally Posted by k0nr4d

Try disabling IPV6 on your router

Thanks but my modem doesn't seem to support it as I can't find any mention of IPV6 in my router. Just curious though did you see something in the logs above that makes you think its an issue with ipv6?

[Marshal]

Disable DNS on the modem for all the connections from the outside, reinstall her Windows (I believe that’s what she’s using) or Android phone, and disable modem error log. If that’s not working, either change a modem or an ISP. Good luck and keep us updated.

[BigFurry]

Looks like some app on her computer is trying to connect to nonexistent domains. It wouldn't be an issue if the modem wasn't buggy.

Option 1.
Set the DNS server in her computer's IPV4 settings to something else than the modem's IP.
Use the ISP's DNS server IP, or Cloudflare's free DNS (1.1.1.1), or Google's free DNS (8.8.8.8 and 8.8.4.4).

Option 2.
Manually add the bad domains to your OS to resolve as a local IP (127.0.0.1).
You can do it in the hosts file. If it's Windows, this one explains how to do it: https://www.thewindowsclub.com/hosts-file-in-windows

Option 3.
Block those domains in the computer's firewall.

Option 4.
Disabling modem log could be a solution too as suggested above.

[2MuchMark]

Originally Posted by Marshal

Disable DNS on the modem for all the connections from the outside, reinstall her Windows (I believe that’s what she’s using) or Android phone, and disable modem error log. If that’s not working, either change a modem or an ISP. Good luck and keep us updated.

Re install Windows? Geezez...

I will check into the rest though, thanks!

Originally Posted by BigFurry

Looks like some app on her computer is trying to connect to nonexistent domains. It wouldn't be an issue if the modem wasn't buggy.

Option 1.
Set the DNS server in her computer's IPV4 settings to something else than the modem's IP.
Use the ISP's DNS server IP, or Cloudflare's free DNS (1.1.1.1), or Google's free DNS (8.8.8.8 and 8.8.4.4).

Option 2.
Manually add the bad domains to your OS to resolve as a local IP (127.0.0.1).
You can do it in the hosts file. If it's Windows, this one explains how to do it: https://www.thewindowsclub.com/hosts-file-in-windows

Option 3.
Block those domains in the computer's firewall.

Option 4.
Disabling modem log could be a solution too as suggested above.

Thanks for the tips. Option 1 makes the most sense to me at the moment. Her computer though has tons of security policies and i'm wondering if switching to 1.1.1.1 may violate any of those. I'm sure its better for her, but need to make sure first. I'll check and let you know how it works out. thanks!!!!

[raymor]

Since you changed the names it's hard to know, but I'd bet her machine is trying to connect to a corporate network that it was set up with. That's the "ldap" part, ldap means "the company authentication server". You may want to remove it from the corporate domain if she no longer works there.