[kstrauser]

It’s pretty sweet. By using ULA addresses for everything, all internal networking keeps working as-is if my ISP allocation changes. Every host can talk to its neighbors using internal addresses, and still connect to remote hosts without NAT breakage.

[fulafel]

You also get this if you use mDNS, but without the ULA hassle and you get to use DNS names instead of hardcoding IP addresses.

[kstrauser]

You can use both. I do.

I do want some hardcoded addresses. In particular, some of the daemons I run get twitchy when the remote address changes unexpectedly.

[esbranson]

mDNS is orthogonal to ULA. mDNS is for discovery and name resolution, whereas ULA is for IP connectivity. And mDNS operates at the link-local scope (link-local addresses), whereas ULA is scoped for the entire home network.

[fulafel]

> mDNS operates at the link-local scope (link-local addresses)

This is not the case for the addresses returned. See eg https://www.rfc-editor.org/rfc/rfc6762

6.2. Responding to Address Queries

   When a Multicast DNS responder sends a Multicast DNS response message
   containing its own address records, it MUST include all addresses
   that are valid on the interface on which it is sending the message,
   and MUST NOT include addresses that are not valid on that interface
   (such as addresses that may be configured on the host's other
   interfaces).  For example, if an interface has both an IPv6 link-
   local and an IPv6 routable address, both should be included in the
   response message so that queriers receive both and can make their own
   choice about which to use.  This allows a querier that only has an
   IPv6 link-local address to connect to the link-local address, and a
   different querier that has an IPv6 routable address to connect to the
   IPv6 routable address instead.

So instead of using static ULA addresses, you can use the the routable address returned by mDNS. It can often replace the ULA address use case.