How to confirm if Microsoft's dns.msftncsi.com is blocking requests from my IP?

Question

I've been fighting the classic "no internet" globe at our primary location for 2 years. It seems to rear it's ugly head every 6-10 months and of course this Monday was a classic explosion of multiple computers not allowing Outlook to function even though the internet was connected. I've spent hours...nay days on this.

Our standard fix has been:

sfc /scannow DISM /Online /Cleanup-Image /RestoreHealth [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NlaSvc\Parameters\Internet] EnableActiveProbing set to 1 [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\NetworkConnectivityStatusIndicator] NoActiveProbe set to 0 `[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\NetworkConnectivityStatusIndicator] DisablePassivePolling set to 1 restart computer

I finally realized that an nslookup with "server 131.107.255.255" to any request fails...pcap shows no response from the server what-so-ever. Confirmed the traffic is being passed by the firewall and no clear blocks from anti-virus.

I can do a DNS request all day from other networks and IPs. I have access to a number of sites and all of them respond instantly to a dns query to the classic nds.msftncsi.com IP. Any recommendations on how to determine if Microsoft is actually blacklisting my primary site IP?

The above fixes have worked previously but of course today, something has changed and 3 computers continue to not function even after the fixes. I think the fact that DNS isn't responding is my smoking gun but I don't know how to resolve it if the server will not respond to my DNS queries.

Answer 1

Hi,

I'd be happy to help you out with your question. Sorry for the inconvenience caused.

To confirm if Microsoft's dns.msftncsi.com is blocking requests from your IP, you can check if the DNS address resolves to 131.107.255.255. If it does not match, then it is assumed that the internet connection is not working. You can also check if NCSI successfully downloads a text file containing "Microsoft Connect Test"

Possibly there is an issue with your DNS resolution, which is preventing your devices from accessing the internet.

Here are a few steps you can take to troubleshoot the issue:

1. Check your DNS settings: You can check this by running the ipconfig /all command on a Windows machine, or by checking the network settings on other devices. You will need to Confirm that the DNS server IP address is correct & that there are no typing mistakes.
2. Test DNS resolution: You can Try to resolve a domain name using nslookup.
3. Check your firewall Settings: You will need to Make sure that your firewall is not blocking DNS traffic. You can try it by temporarily disabling the firewall and seeing if DNS queries are successful.
4. Check your network configuration : You will need to Make sure that your devices are correctly configured for your network, including IP addresses, subnet masks, and default gateways.

For More Information please refer to :- https://learn.microsoft.com/troubleshoot/windows-client/networking/internet-explorer-edge-open-connect-corporate-public-network

If you have any other questions or need assistance with anything, please don't hesitate to let me know. I'm here to help.

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