Migration ISC DHCP –> Dnsmasq – Bug or Feature ?

[JDabbs]

I have been running Opnsense for 18 months in dual stack IPv4 & IPv6 without issue using the as was default of
ISC DHCPv4
Unbound DNS
Router Advertisements (IPv6) & Track Wan interface.

Recently I have become aware that ISC DHCP is coming to the end of it's life so I thought I would migrate to the current Opnsense recommended "standard" of

Dnsmasq DHCP (to replace ISC)
Unbound DNS
Router Advertisements (IPv6) & Track Wan interface.

I have read through the official documentation and an article & YouTube video from the "Home Network Guy" and set up Dnsmasq as per both (the Home Network Guy based his article and YouTube video on the official Opnsense documentation) leaving IPv6 untouched tracking the WAN interface and using SLAAC.

In short disabled ISC DHCPv4 (wasn't using ISC DHCPv6 as using SLACC) then configured & enabled Dnsmasq. Unless I have missed something it's configured exactly as per the Opnsense documentation, that's not to say I haven't missed something.

As I already had some Unbound DNS Overrides set up for IPv6 to enable local IPv6 name resolution I left these alone.
Internet access worked fine no issues both IPv4 & IPv6 working as expected.

Now the question, bug or feature? Local name resolution worked fine but only returned IPv6 addresses where there was an Unbound DNS override set. Remember I had set overrides for only IPv6 addresses because of SLACC not IPv6 DHCP so Opnsense didn't know of the hostname to IPv6 association as it wasn't involved in the address allocation.

Previously when using ISC DHCPv4 with IPv6 overrides set,  Opnsense returned both IPv4 & IPv6 addresses in response to DNS queries for the LAN. However now it only returns IPv6 addresses to client requests to DNS. I have found that by creating an IPv4 overrides as well as IPv6 ovrrides it does return both v4 & v6 addresses.

Given that previously under ISC DHCP it only needed the IPv6 override to supply the IPv6 address for a DNS query, ISC DHCP was already aware of the IPv4 address to hostname address as it had issued it, I had expected Dnsmasq to function in the same way but it appears not to.
Is this a bug or a is this how it's intended to work. If I disable an override for a host Opnsense returns the IPv4 address.

In ISC DHCPv4 & Unbound,  overrides appeared to work in an additive capacity (providing an IPv6 address in addition to the static IPv4 address assigned by ISC DHCPv4). When using Dnsmasq and Unbound DNS the overrides appear to "override" Dnsmasq.

It's not a problem as it's possible to create both an IPv4 & IPv6 override in Unbound DNS and both work. My question is have I mis-configured something or is this how it's intended to work or is there a bug?


PS running the slightly out of date 25.7.7.4 wanted to sort this and get it working before updating to the latest version & I started the migration before the latest release.

PPS this is only a local LAN DNS issue the WAN and internet works fine returning both IPv4 & IPv6 addresses depending on the site.