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    Server 2019 randomly DNS stops

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    • ObsolesceO
      Obsolesce @choppy_sea
      last edited by

      @choppy_sea said in Server 2019 randomly DNS stops:

      @Obsolesce Lots of informational logs but not error or critical logs. I've looked through those and most of them say "I can't find x" because no DNS.

      There are a lot of informational logs for directory sync but I'm not able to spot any specific events that look like a trigger.

      I meant on the DNS server, the DNS operational logs.

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      • ObsolesceO
        Obsolesce @choppy_sea
        last edited by

        @choppy_sea said in Server 2019 randomly DNS stops:

        Forwarders are set to Google and OpenDNS

        Can u show the screen where this is set

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        • DashrenderD
          Dashrender
          last edited by

          Is DNS not resolving only for the RDS server or does it happen for any device on the network? i.e. laptop trying to use DNS directly.

          C 1 Reply Last reply Reply Quote 0
          • J
            JasGot
            last edited by

            Is the DNS Server the Domain Controller?
            Is the VM Host a member of that domain?

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            • notverypunnyN
              notverypunny @choppy_sea
              last edited by

              @choppy_sea said in Server 2019 randomly DNS stops:

              @notverypunny said in Server 2019 randomly DNS stops:

              DNS server / Domain Controller

              No I inherited this unfortunately ! I'm sure we've all been here..

              1. DHCP scope is configured with Router, DNS Servers (as the AD DNS ONLY) and DNS domain name of domain.co.uk - I mean it looks correct.
              2. Clients get DNS from AD DNS server through DHCP as above and to my knowledge noone is capable of changing it on their desktops.
              3. AD DNS server isn't set to loopback no, its set to its own IP (which is what I thought was properly configured)
              4. Forwarders are set to Google and OpenDNS

              I totally agree about the host reboot thing, its is in my opinion the most puzzling thing. Maybe I should retest that theory encase the times it hasn't worked is a fluke...the internet is a wireless link provided by a small ISP here in the UK and I'm not familiar with their service.

              The whole thing is a huge headache. I've tried uninstalling my RMM tool encase that is the issue. I have noticed that when I teamviewer in sometimes that seems to either trigger it or I'm super (un)lucky...

              Yeah, sorting out an inherited mess is never fun.

              When things stop working, can you still ping out to known good IPs? I.E. 8.8.8.8 1.1.1.1 etc? Maybe DNS isn't the problem. You mention that it's a small WISP, maybe their CPE can't handle the connection load and similar to my rate-limiting theory it's just a coincidence that the time taken to reboot the host and guests is enough to clear the CPE's session table.....

              I'll add my vote to those strongly recommending a deep dive on the DNS server's logs, and I'll throw the Host system's logs in there too for good measure.

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              • C
                choppy_sea @Dashrender
                last edited by

                @Obsolesce DNS logs show one interesting one linked, the log says that its transferred the master role from itself to itself https://imgur.com/a/4I75qnB if you mean somewhere else I apologise!

                @Dashrender It happens for every device on the network!

                @JasGot Yes the AD server does DNS and DHCP too, yes the Host on the domain

                @notverypunny When I ping a known good IP i.e. 8.8.8.8 I get "...unreachable" rather than the "Ping request could not..."

                DashrenderD notverypunnyN 2 Replies Last reply Reply Quote 0
                • DashrenderD
                  Dashrender @choppy_sea
                  last edited by

                  This post is deleted!
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                  • ObsolesceO
                    Obsolesce
                    last edited by

                    Do you lose dns and/or network abilities on the DNS server too?

                    C 1 Reply Last reply Reply Quote 0
                    • C
                      choppy_sea @Obsolesce
                      last edited by

                      @Obsolesce yes, the only way I can connect to it is through the hosts Hyper-V and the shares on the AD server drop

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                      • DashrenderD
                        Dashrender
                        last edited by

                        Tell us about your network setup... switches firewall, APs

                        C 1 Reply Last reply Reply Quote 0
                        • DashrenderD
                          Dashrender
                          last edited by Dashrender

                          If noting on the network is working, that makes me think a bad switch.
                          Or possibly a bad NIC taking down your switch.

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                          • C
                            choppy_sea @Dashrender
                            last edited by

                            @Dashrender Draytek 2860 (being replaced this week) - 3 * unifi switches (fibre linked) and a few rando APs dotted around. It's quite a simple setup, the APs are a bit sus. I could pull them all out...

                            DustinB3403D 1 Reply Last reply Reply Quote 0
                            • DustinB3403D
                              DustinB3403 @choppy_sea
                              last edited by

                              @choppy_sea said in Server 2019 randomly DNS stops:

                              @Dashrender Draytek 2860 (being replaced this week) - 3 * unifi switches (fibre linked) and a few rando APs dotted around. It's quite a simple setup, the APs are a bit sus. I could pull them all out...

                              Why are the AP's sus?

                              C 1 Reply Last reply Reply Quote 0
                              • C
                                choppy_sea @DustinB3403
                                last edited by

                                @DustinB3403 they're cheapo TP-Link routers acting as APs (they have an AP mode) I think they are sus because technically they are capable of DNS and DHCP themselves...could be one going rouge 😕

                                DustinB3403D 1 Reply Last reply Reply Quote 1
                                • DustinB3403D
                                  DustinB3403 @choppy_sea
                                  last edited by

                                  @choppy_sea said in Server 2019 randomly DNS stops:

                                  @DustinB3403 they're cheapo TP-Link routers acting as APs (they have an AP mode) I think they are sus because technically they are capable of DNS and DHCP themselves...could be one going rouge 😕

                                  Oh! Sorry I misread, I thought you said Unifi AP's but you said Unifi switches.

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                                  • notverypunnyN
                                    notverypunny @choppy_sea
                                    last edited by notverypunny

                                    @choppy_sea said in Server 2019 randomly DNS stops:

                                    @Obsolesce DNS logs show one interesting one linked, the log says that its transferred the master role from itself to itself https://imgur.com/a/4I75qnB if you mean somewhere else I apologise!

                                    @Dashrender It happens for every device on the network!

                                    @JasGot Yes the AD server does DNS and DHCP too, yes the Host on the domain

                                    @notverypunny When I ping a known good IP i.e. 8.8.8.8 I get "...unreachable" rather than the "Ping request could not..."

                                    OK, so if you can't even get out by IP, then strictly speaking DNS isn't the issue. Lower level TCP/IP or something else in the network is a problem before DNS even comes into play. Even if your DNS is completely offline you should be able to ping 8.8.8.8 or 1.1.1.1

                                    I'd setup a standalone machine on the network with a static IP and have it pointed to external DNS. If it stops working when everything else does, then you know that it's something in your LAN > WAN setup. If it keeps working when everything else goes sideways then you're looking at the possibility of something wrong along the lines of the rogue DHCP that you've alluded to or other LAN-side gremlins. Don't rule out the possibility of a user having connected something that's doing all kinds of fun DHCP garbage.... Users can be... "special"

                                    DashrenderD jt1001001J 2 Replies Last reply Reply Quote 1
                                    • DashrenderD
                                      Dashrender @notverypunny
                                      last edited by

                                      @notverypunny said in Server 2019 randomly DNS stops:

                                      @choppy_sea said in Server 2019 randomly DNS stops:

                                      @Obsolesce DNS logs show one interesting one linked, the log says that its transferred the master role from itself to itself https://imgur.com/a/4I75qnB if you mean somewhere else I apologise!

                                      @Dashrender It happens for every device on the network!

                                      @JasGot Yes the AD server does DNS and DHCP too, yes the Host on the domain

                                      @notverypunny When I ping a known good IP i.e. 8.8.8.8 I get "...unreachable" rather than the "Ping request could not..."

                                      OK, so if you can't even get out by IP, then strictly speaking DNS isn't the issue. Lower level TCP/IP or something else in the network is a problem before DNS even comes into play. Even if your DNS is completely offline you should be able to ping 8.8.8.8 or 1.1.1.1

                                      I'd setup a standalone machine on the network with a static IP and have it pointed to external DNS. If it stops working when everything else does, then you know that it's something in your LAN > WAN setup. If it keeps working when everything else goes sideways then you're looking at the possibility of something wrong along the lines of the rogue DHCP that you've alluded to or other LAN-side gremlins. Don't rule out the possibility of a user having connected something that's doing all kinds of fun DHCP garbage.... Users can be... "special"

                                      Rogue DHCP won't cause a universal issue like this all at once unless all the leases came up for renewal at the same time. Then on top of that, unless the rogue is on the VM host, he's not indicated he's done anything that would remove it from the network - like rebooting all APs/switches.. only reboot mentioned is the VM host.

                                      I'm wondering if you have a bad NIC causing the switch that connects to your firewall to overload? or the switch itself is bad and flaky, but again, no mention of rebooting the switch to make things work again.

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                                      • DashrenderD
                                        Dashrender
                                        last edited by

                                        Next time you take the server down, before rebooting it - unplug it's network cables and use another device to try to ping 8.8.8.8

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                                        • jt1001001J
                                          jt1001001 @notverypunny
                                          last edited by

                                          To back up @notverypunny when I have seen this behavior on our network, 99% of the time its rogue piece of equipment that starts handing out its own DHCP conflicting with ours. Check that users are NOT plugging in or connecting non approved devices, like travel routers or other router devices. We install a lot of equipment ofr custoemrs that our techs are suppsoed to plug into "isolated' networks and usually the , um "forget"

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                                          • C
                                            choppy_sea @Dashrender
                                            last edited by

                                            @Dashrender @notverypunny Good ideas! Thanks!

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