I received the work network with a TLD set up to be .local, so all the hosts on the LAN have FQDNs of host.businessname.local.
It certainly looked “official”, but mDNS uses the .local tld for its own purposes.
I was trying to get our samba server up into the AD and was having a problem joining the domain.
DNS wasn’t going to resolve FQDNs that end in .local because it doesn’t recognize it as a TLD.
The quick fix was to add the hostname to the /etc/hosts file.