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valtrig

Member

From: Athens, Greece

Registered: 2017-03-16

Posts: 3

Issue with Avahi and new version of nss-mdns

After my system got updated to the latest version of nss-mdns last week, I discovered that mDNS name resolution using the .local domain did not work any more. Further investigation showed that the issue was related to one of the resolution limiting heuristics introduced by nss-mdns after version 0.10, specifically, the unicast SOA heuristic. In my case, the output of host -t SOA local returns:

local has SOA record localhost. root.localhost. 1 604800 86400 2419200 86400

Similarly, using nslookup -type=SOA local:

Server:		172.22.250.244
Address:	172.22.250.244#53

Non-authoritative answer:
local
	origin = localhost
	mail addr = root.localhost
	serial = 1
	refresh = 604800
	retry = 86400
	expire = 2419200
	minimum = 86400

Authoritative answers can be found from:
localhost	internet address = 127.0.0.1

I managed to solve the problem by whitelisting .local in /etc/mdns.allow, as described in the aforementioned URL, and also by switching from the mdns4_minimal  module to the full mdns4 in /etc/nsswitch.conf. The thing is, I am not sure if this is a "proper" solution for this issue. The server shown above is actually the primary domain controller of our company's ActiveDirectory network. As far as I know, the TLD of all machines that are joined in the AD is .private. My machine is not part of AD and only gets an IP address and the name-server settings via DHCP, which is why I needed Avahi/mDNS.

Basically I have the following questions:

1. Does the above non-authoritative answer indeed come from the name-server? If so, is this considered normal practice or is it caused by some DNS zone misconfiguration regarding the .local TLD (for example, see an old, somewhat related Avahi bug), in which case I should contact our network admin with the issue?

2. If the above response is not coming from the name-server, do all those "localhost" and "127.0.0.1" field values mean that this record somehow comes from my own PC's network stack, meaning that it is actually my PC that is misconfigured?

Thanks in advance for any help!