[dns-operations] Link-local IP addresses for a resolver?

[Tony Finch]

John Levine <johnl at taugh.com> wrote:
>
> How are they with RFC 4193 ULAs?  I've been using a cache at a ULA on
> my two-segment home network and it seems to work fine.

I would expect them to "just work" modulo the network connectivity issues
associated with ULAs mentioned by Mark.

The problem with link-local addresses is "which link?" so to answer that
the resolver address has to be scoped. When I looked, the common problem
was to store the resolver address as 16 bare bytes which lacks space for
the interface scope, rather than sockaddr_in6 which includes the scope and
other complications. That's if the code parsed and ignored the scope; it
was also common to simply fail to parse the scoped address.

I also have vague worries about lurking bugs with RDNSS and DHCPv6
resolver configuration: the addresses on the wire are bare and only
implicitly scoped to the interface they arrived on, which offers so many
opportunities to make mistakes.

Tony.
-- 
f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
Thames, Dover, Wight, Portland, Plymouth: Southwesterly 5 to 7, occasionally
gale 8 at first in Thames, Dover and Wight. Slight or moderate in Thames, but
elsewhere mainly moderate or rough, although very rough at first in southwest
Plymouth. Rain or showers. Good, occasionally poor.