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multiple A/AAAA with dynamic updates

Started by dseomn, September 20, 2021, 10:24:46 AM

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Is there any way to have a single name with multiple A or AAAA records pointing at different places with separate dynamic updates? I tried making two separate names with separate dynamic updates, then pointing two ALIAS records from the same name to those dynamic names, but I'm only getting a single record when I look up the ALIAS name.

Dynamic records:

uriel.mandelberg.org A 300
chusuk.mandelberg.org A 300

Static records:

test123.mandelberg.org ALIAS 300 uriel.mandelberg.org
test123.mandelberg.org ALIAS 300 chusuk.mandelberg.org

$ host test123.mandelberg.org
test123.mandelberg.org has address

Is there any way to set up a name that returns records for both addresses above, where each address can be changed separately by a different dynamic dns client?


Probably not.  The whole point of a dynamic address update is that any (and all) prior address(es) are invalid when the record is updated with a new address.  You must use separate labels to maintain more than one dynamic destination (one label per destination).  IPv4 and IPv6 dynamic addresses can coexist under a single label because they are different RR-types.

ALIAS, CNAME, and DNAME records take a single destination only.  Multiple instances of these RR-types are forbidden.

If you're trying to do something like load balancing or failure rollover, look at SRV records if the application or protocol you intend to use supports them.


I thought ALIAS wasn't a real record type, so the DNS server software could do whatever it wanted to do with it? I want failover for HTTPS, so I don't think there's anything like SRV that would work for that.


It can't hurt to add them in the hope that someday HTTP will support them, but don't hold your breath.