1

I'm trying to do DDNS. I have two Apple products: an Airport Extreme and a Macbook Air, and I want to update my DDNS server via the "Dynamic Global Hostname" feature.

I setup DDNS in the cloud (BIND), and via my local Ubuntu machine (nsupdate version is, apparently, "nsupdate: illegal option -- V", I can simply say:

nsupdate -D -k [TSIG key path]
> update add jeff-laptop-2013.ddns.mydomain.com 86400 A [my IP]
> send
Found zone name: ddns.mydomain.com
The master is: ns1.ddns.mydomain.com
send_update()
Sending update to [IP address of cloud DNS server]#53

and it correctly sends an update to the authoritative nameserver ns1.ddns.mydomain.com.

However, on my OS X laptop (the one I want to update via Dynamic Global Hostname, nsupdate version 9.10.1-P1), it insists on sending it to my "main" DNS server (unless I specify the NS), rather than the authoritative NS:

> send
Found zone name: ddns.mydomain.com
The master is: ns1.ddns.mydomain.com
send_update()
Sending update to 8.8.8.8#53

(ns1.ddns.mydomain.com does not resolve to 8.8.8.8.) This fails with:

; TSIG error with server: expected a TSIG or SIG(0)
show_message()

Reply from update query:
;; ->>HEADER<<- opcode: UPDATE, status: SERVFAIL, id:   3677
;; flags: qr ra; ZONE: 1, PREREQ: 0, UPDATE: 0, ADDITIONAL: 0
;; ZONE SECTION:
;ddns.mydomain.com.         IN  SOA

This might be why the Dynamic Global Hostname (occasionally, but not reproducibly) prints the following error:

2/7/15 10:55:43.623 AM discoveryd[27932]: Basic DNSResolver UDNS Send(): UDP Sendto() failed to DNSNameServer 8.8.8.8 Port 53 errno 49, fd 42, ErrLogCount 2 ResolverIntf:0

I'm not familiar with BIND or Dynamic Global Hostname. Is this a bug? How could I look into this problem? Any suggestions?

0

Yes, it appears to be related to this bug.

https://kb.isc.org/article/AA-01220/0/nsupdate-in-BIND-9.9.6-9.10.0-and-9.10.1-fail-to-resolve-the-SOA-MNAME-in-some-cases.html

Also, I think they key type must be HOST, not ZONE (the default for dnssec-keygen) or USER.

  • At some point, my brew updated nsupdate to version 9.12.1-P2, and it works as expected. – Jeff Jun 22 '18 at 4:00

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