DNS server not responding intermittently

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Curiosity Technology Computers and Smartphones DNS server not responding intermittently

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  • I have a modem that connects to my ISP (BSNL). Since the past week, the modem was acting weird. When the DSL connects, it stays around for a while until the modem establishes an internet connection. But right after a successful connection, the DSL drops and tries to connect again. Disconnected the Ethernet cable and tried. Same results.

    Tried another modem. Same results. DSL drops right after making a connection to the internet.

    I tried a third modem (without wifi). This time the DSL stays on forever after the internet connection is established. But other sorts of problem arises with DNS. Despite the DNS servers set, the resolution fails often. Especially when I switch between applications and browser.

    1. Tried setting DNS to Google/OpenDNS. Same results.
    2. Ran all these:

    ipconfig /flushdns
    ipconfig /registerdns
    ipconfig /release
    ipconfig /renew
    NETSH winsock reset catalog
    NETSH int ipv4 reset reset.log
    NETSH int ipv6 reset reset.log

    Issues persist!

    1. Checked for any proxies set. None found.
    2. Restarted DNSClient and DHCPClient services and tasks. No joy!
    3. The DNS failure is 100% when I open and close the torrents.
    4. When there’s a DNS resolution error in the browser, I can still ping (ICMP) the servers with a successful response.
    5. I have checked the MTU limit and there are no packet losses.
    6. I have checked for malware. None found.
    7. Installed wireshark and analyzed the connections. Nothing out of the ordinary.
    8. Checked with different browsers (Chrome, FF, FF Nightly, Chrome Canary, Edge)
    9. System File Checker Scan shows no issues.
    10. I did not install any programs lately.
    11. Contacted the ISP on multiple occasions and they were kind enough to reset my phone line multiple times. They have also confirmed that my line is fully operational without any issues.
    12. Checked my hosts file. Other than Microsoft’s telemetry servers there are no rules set for any of the sites. Tried with clean hosts file too. Same results!
    13. Troubleshooter finds no issues.

    Also,
    1. All my drivers are up to date.
    2. Windows is up to date.
    3. No attenuation in my lines.

    I have no more options to try. I am starting to think this is an issue with my network config.

    Additional Details:
    OS: Windows 10
    Current DNS: Google Public DNS (now set at router)
    DHCP: Enabled
    Default Gateway: 192.168.1.1
    DHCP Server: 192.168.1.1
    NetBT: Enabled

  • You really had tried it all! This is a very good overview! There are still a few things you can try.

    1. Try power cycling the modem (I suppose you might have done this already!)
    2. Try booting the system in safe mode with networking and check if the issue can be reproduced
    3. Check for any firmware updates for your modem

    Incase you haven’t tested other devices, do that. If the DNS fails on other devices too, then it’s more likely an issue with your router or ISP.

    • Try power cycling the modem (I suppose you might have done this already!)

      Yes, I have done this many times.

      Try booting the system in safe mode with networking and check if the issue can be reproduced

      I should have mentioned this earlier. I did try this and the issue persists.

      Check for any firmware updates for your modem

      No firmware updates for this model. This model is fairly old. Like 5 years old!

      Incase you haven’t tested other devices, do that. If the DNS fails on other devices too, then it’s more likely an issue with your router or ISP.

      I will update on this when I get hold of a friend’s laptop.

    • Okay! I tried everything. This happens on my friend’s laptop too. I think it’s the router. For further support, I have added a thread here. Thought it would be helpful.

  • It is the router. I replaced it and now all works fine.

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