FOG Server IP Keeps Changing in DNS!



  • When I deployed our FOG server, I chose an IP in advance and configured the server to use that static IP as I was deploying it. I created a static host entry in our AD DNS, and everything seemed fine... Until I noticed that the host record and IP reverted back to the original DHCP IP (FOG will always pick up a DHCP IP prior to setting a static IP and finishing the deployment).

    I've verified in the FOG web console that the IP is still correct (the static IP I assigned), and I also double-checked the .fogsettings file to make sure that the IP is correct there as well. One last ditch effort I did was I deleted the A and PTR records in DNS and verified that the deletion successfully replicated across all internal DNS servers, then I created a fresh A record (which automatically created a fresh PTR record). I let the addition replicate and waited a couple days to see if that fixed the issue; it did not! A couple days after doing this, the IP has reverted back to the original DHCP address, and it's not pingable. If I ping the server by the correct IP, it works (but the DNS name is obviously wrong)

    Why is this happening, and what can I do to fix it!?



  • I've never heard of this issue. Do you have two NICs attached to the FOG server?

    The other point is to create a static assignment in your DHCP server associated with the FOG server's NIC. That will resolve the issue of grabbing an IP address other then the one statically assigned.



  • What Linux distro is FOG installed on?



  • @coliver Nope - only one NIC (and this server is a guest VM).

    @black3dynamite Ubuntu 16.04.1 LTS (64-bit)



  • I went ahead and created a DHCP reservation for the server (even though the server is configured for a static IP), and as soon as that was successfully created, the A record vanished in DNS (not what I was expecting to see happen). I went ahead and manually created the A record again, and I left the DHCP reservation in place, but obviously the reservation will not be of much use unless I change the server to use a DHCP assigned IP instead of a static one (something I'd really rather not do)...



  • Within your server have you edited /etc/network/interfaces to be statically assigned?



  • @DustinB3403 Yep, prior to configuring FOG:
    auto ens160
    iface ens160 inet static
    address <hidden>
    netmask <hidden>
    gateway <hidden>



  • @Shuey hrm. . .

    And it's still getting a DHCP address. Are you sure the interface is named ens160?



  • @DustinB3403 I thought I clearly stated in my original post that it's not getting a DHCP address; it's been configured with a static IP ever since I installed FOG. And yes, the interface is named "ens160" (confirmed with ifconfig).



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @DustinB3403 I thought I clearly stated in my original post that it's not getting a DHCP address; it's been configured with a static IP ever since I installed FOG. And yes, the interface is named "ens160" (confirmed with ifconfig).

    You keep saying it's defaulted back to the original DHCP address.

    This means that it is not accepting the reservation, or B you've misconfigured the interface.

    If you've confirmed the interface is named "ens160" then the last question is why would the system revert to searching for DHCP.



  • @DustinB3403 The FOG SERVER is not defaulting back to the DHCP address, our AD DNS is where the IP keeps reverting back (and this is all BEFORE ever creating a dedicated reservation that matches the correct IP).



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @DustinB3403 The FOG SERVER is not defaulting back to the DHCP address, our AD DNS is where the IP keeps reverting back (and this is all BEFORE ever creating a dedicated reservation that matches the correct IP).

    The delete all DNS records for the fog server, and let it be found the natural way.

    With time.



  • @DustinB3403 If a non-domain server is configured with a static IP, the host record won't get automatically created in AD DNS... How is it supposed to be "found the natural way - with time" when it'll never be discovered automatically :-S...?



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @DustinB3403 If a non-domain server is configured with a static IP, the host record won't get automatically created in AD DNS... How is it supposed to be "found the natural way - with time" when it'll never be discovered automatically :-S...?

    DNS isn't dependent on AD.



  • @Shuey Do you have Dynamic updates set to Secure only or Nonsecure and secure?



  • @black3dynamite "Nonsecure and secure"


  • Service Provider

    Okay, so to recap... there is NO issue on the FOG system and the entire thread is actually about a problem with Windows DNS getting bad updates. The AD DC is running DNS, and DNS keeps showing an A record for the FOG server that is the old DHCP assigned address for that rather than the current statically assigned one?



  • @scottalanmiller Pretty much, yep. I say "pretty much" because I'll also re-clarify that the entry in DNS is accurate for a couple of days, and then it suddenly changes to the FOG server's old DHCP address.

    Here's a recap of the server's DNS record:

    1. The Ubuntu server picked up a DHCP address when the server was first setup (prior to FOG getting installed and configured).
    2. That address then appeared in DNS as I would expect, but of course was the wrong IP (since it was not statically assigned yet).
    3. I configured the Ubuntu server with a static IP, then I updated the DNS record, making it static instead of DHCP assigned (as well as the PTR), then installed and configured FOG (using the same static IP of course).
    4. I thought everything was fine, but a couple days later I noticed that I couldn't ping the FOG server. I checked DNS and noticed that the static entry I had configured had changed to the original DHCP address that the Ubuntu server had picked up....


  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @black3dynamite "Nonsecure and secure"

    Have you already try setting it to secure only and then delete dns record?



  • Your Ubuntu Server DNS setting is probably configured with your DNS Server IP.



  • @black3dynamite Nope :-/... DNS in our environment has always been configured for "nonsecure and secure" and I've never changed it because I'm not familiar with how to properly set it to "secure only", nor am I familiar with what kind of repercussions there would be :-S...



  • @black3dynamite I'm trying to check the DNS settings right now, but oddly enough, I can't login anymore... (I just rebooted the server and after it came back up, I'm not able to login to the CLI). I can still login to the web console no problem, but the CLI creds are not working O_o...



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @black3dynamite I'm trying to check the DNS settings right now, but oddly enough, I can't login anymore... (I just rebooted the server and after it came back up, I'm not able to login to the CLI). I can still login to the web console no problem, but the CLI creds are not working O_o...

    The issue is clearly your DNS server then :-)



  • @DustinB3403 Now I'm crazy confused... what does me not being able to login to the CLI have to do with my AD DNS? O_o



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @DustinB3403 Now I'm crazy confused... what does me not being able to login to the CLI have to do with my AD DNS? O_o

    You said you weren't able to access the server, didn't you?



  • @DustinB3403 No... I think you should slow down and read what I say before you reply, lol. I said "I can still login to the web console no problem"... I'm NOT able to login to the CLI (because my password is failing, not because I can't GET to the CLI :-/...



  • @Shuey said in FOG Server IP Keeps Changing in DNS!:

    @DustinB3403 No... I think you should slow down and read what I say before you reply, lol. I said "I can still login to the web console no problem"... I'm NOT able to login to the CLI (because my password is failing, not because I can't GET to the CLI :-/...

    Could be, I'm not really paying attention to ML atm.



  • OK, so I gained access to the CLI again. There doesn't appear to be any DNS servers configured for my Ubuntu server to talk to (even though it can get out to the Internet for updates without any problem, because it at least has a gateway configured).

    This seems to rule out black3dynamite's theory that my Ubuntu server DNS is configured with my DNS server IP...

    Where else should I check for these settings, besides in /etc/network/interfaces ??


  • Service Provider

    @Shuey said in FOG Server IP Keeps Changing in DNS!:

    OK, so I gained access to the CLI again. There doesn't appear to be any DNS servers configured for my Ubuntu server to talk to (even though it can get out to the Internet for updates without any problem, because it at least has a gateway configured).

    This seems to rule out black3dynamite's theory that my Ubuntu server DNS is configured with my DNS server IP...

    Where else should I check for these settings, besides in /etc/network/interfaces ??

    DNS is shown in the file /etc/resolv.conf


  • Service Provider

    If you do an nslookup command, it will show you which DNS server it queried at that time, as well.


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