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Facing an issue we've not faced before; the problem concerns an onsite premise.

Tha Lan is setup around a simple domain environment. 2 Domain controllers (Primary and secondary), each having a DNS. This morning all hosts were discarded automatically from the DNS and we were no longer able to ping most of the devices over IPv4. On the other hand IPv6 works.

Any idea to why:

  1. We're unable to ping any IPv4 but able to ping IPv6 (We get the IPv4 address by going on every machine and typing ipconfig on command line)?
  2. The A records belonging to client PCs were discarded from the DNS.

All client computers are able to browse the internet and ping the gateway but not other internal devices.

When executing ipconfig /registerdns from my client pc I get the following error in event viewer:

The reason the system could not register these RRs was because the DNS server contacted refused the update request. The reasons for this might be (a) you are not allowed to update the specified DNS domain name, or (b) because the DNS server authoritative for this name does not support the DNS dynamic update protocol.

Thanks in advance.

  • Are these Windows domain controllers? If they are providing DNS services for your local network, do they also provide DHCP? When you say you are unable to ping IPv4, do you simply mean that you're not able to resolve hostnames to IPv4 addresses (as the DNS has failed) or that you're attempting to ping known IPv4 addresses directly and it's still not working? If you directly inspect your other hosts, do they still have IPv4 addresses configured? – Carcer Mar 30 '17 at 8:35
  • @Carcer many thanks for your reply. Yes it's a Windows domain environment. Yes both DNS and DHCP service provided by the same domain controllers. By unable to ping IPv4, I would be testing it by typing ping x.x.x.x from cmd. I know the client PC's IP because I can check them as we're in the same office. All hosts on the same network are unable to ping or be pinged. – joebegborg07 Mar 30 '17 at 8:41
  • Do the PCs actually still have any IPv4 addresses? Log in remotely and check. Remember that Windows was designed to operate without IPv4 addresses or even with IPv4 disabled. If all the PCs lost their IPv4 addresses, it's time to look at the DHCP (v4) server. – Michael Hampton Mar 30 '17 at 9:36
  • @MichaelHampton thanks for your reply. All devices have IPv4 address they're just unable to ping other LAN PCs and also the DNS server is not listing the computers in the domain environment. – joebegborg07 Mar 30 '17 at 9:39
  • Are the IPv6 addresses also missing from DNS? And, being unable to ping doesn't really mean much since the Windows firewall blocks it by default. – Michael Hampton Mar 30 '17 at 9:40

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