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Need help with DDNS on IPv6

Rohith050 1 Reputation point
2020-08-19T11:23:37.607+00:00

Hi,
Need some help with DDNS on IPv6.
I have a small network with DHCP server hosted on a windows machine and a dns server hosted on linux. Most of the clients are linux and there is no Domain controller for this network. DHCP server is also not part of any domain

My aim is to setup DDNS updates for both IPv4 (A) and IPv6(AAAA). Linux client hostname is given as 'testhost'.

For ipv4, i have created a reservation for linux client and provided option 15 (Domain name) as 'testdomain.com' and option 06 (dns server) as linux dns server IP

DNS server has a zone created for 'testdomain.com' and it is configured to accept updates from DHCP server.

When the linux client goes through dhcpv4 process, client sends hostname(testhost) in discover message and windows servers assigns an IP, triggers DDNS updates to DNS server for A and PTR records with FQDN as "testhost.testdomain.com"

So it kind of works for IPv4 but i am stuck in IPv6

In DHCPv6 process, linux client sends FQDN option (39) with S flag set and FQDN as 'testhost'. As per RFC, if the FQDN is partially filled, servers SHOULD respond with complete FQDN.

But what i do not understand is that, how the FQDN is formed in DHCPv6. Unlink DHCPv4, DHCPv6 does not have "domain name" option. DHCPv6 does have "domain search list" option but i am not sure how/if this will be used in forming FQDN. In my case, windows DHCP server responds with same FQDN value ('testhost') as sent in solicit message.

And also, in my case, windows does not trigger DDNS update for AAAA record but it does trigger an update for PTR record with IPv6 IP mapped to partial FQDN ('testhost' in this case)

Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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  1. Candy Luo 12,691 Reputation points Microsoft Vendor
    2020-08-20T06:31:32.817+00:00

    Hi ,

    Based on my understanding, your issue is that IPV6 AAAA records do not get registered by DHCP. Is that right?Please feel free to let me know if my understanding is wrong.

    How about windows machine?

    In order to narrow the issue, please first check if the windows machine can register their IPV6 AAAA records successfully.

    Also make sure on the IPv6 Properties > DNS tab, the following options are set:

    • Enable DNS Dynamic Updates According to the Settings Below:
    • Always Dynamically Update DNS AAAA and PTR Records
    • Discard AAAA and PTR Records when Lease is Deleted

    ---Please Accept as answer if the reply is helpful---

    Best Regards,

    Candy

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