RUTX10 : DNS Dynamic Update (RFC 2136) not working with Windows Server DHCP

Networking Solutions
1

Hello,

I am experiencing an issue with DNS dynamic updates on a Windows Server DNS/DHCP environment when Teltonika devices operate as DHCP clients.

Context :

  • The Windows DHCP server assigns an IP address to the Teltonika device correctly.

  • However, the corresponding DNS records (A/AAAA and PTR) are not created or updated automatically via Dynamic DNS Updates.

  • Windows DHCP and DNS rely on the mechanism defined in RFC 2136 (“Dynamic Updates in the Domain Name System”), which is also used by BIND (via nsupdate).

  • When using an OpenWrt device as a DHCP client, DNS updates on Windows Server work out of the box, which confirms that the server-side DNS/DHCP configuration is functioning normally.

  • This suggests that the Teltonika DHCP client is either not sending the proper FQDN information (DHCP Options 12/81), or is not initiating a compliant dynamic DNS update process.

In my last issue (RUTX10 - DNS registering - Networking Solutions - Teltonika Community) I couldn’t get if you had a Windows Server environment…

Found also other topics

Bind-nsupdate aka RFC2136 - Networking Solutions - Teltonika Community

RFC2136 dynamic dns update (bind-nsupdate) - Networking Solutions - Teltonika Community

Thanks for your help.

3

Hello,

Our devices do not support option 81 as clients, only as servers. However, the option 12 is being sent (we double checked it via Wireshark), so what you can do as a workaround, is edit your WAN interface (since that’s how you’re probably receiving an IP address in the first place) and change the Hostname to send when requesting DHCP:

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This one is dependant on the server settings, more specifically, the lease time that is set on the server when leasing out IPs to the clients.

Regards,
M.

4

Hello Matas,

Thanks for your reply.

Changing the hostname sent when requesting DHCP didn’t work.

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We are using RUTX10 for OT separation.

Thanks for your help.

5

Hi there,

Could you share the OpenWRT version you’re currently using on the other router, as well as the network configuration & the dns/DHCP-related configurations? There shouldn’t be a difference in how these things work between RutOS and OpenWRT, so we would just like to confirm these details.

Regards,
M.