FreeBSD-11 local_unbound stops resolving

[James B. Byrne]

I have a reoccurring issue with my recently installed FreeBSD
workstation.  The local_unbound dns service ceases to provide dns
entries to the local resolver after some period of time; measured in
many hours or days.  I have checked the pf firewall logs and that is
not blocking any traffic relating to DNS that I can detect.

If I re-run local-unbound-setup then local_unbound again resolves.  If
I restart the local_unbound service then dns resolution again works.

I cannot see anything in /var/log/messages that indicate that the
unbound service has a problem and the service is indeed running when I
encounter the issue.

We have many other FreeBSD-11 hosts running local unbound and I have
not noticed this issue anywhere else.

This is the resolv.conf file
# cat /etc/resolv.conf
search harte-lyne.ca hamilton.harte-lyne.ca brockley-2016.harte-lyne.ca
nameserver 127.0.0.1
nameserver 216.185.71.33
nameserver 216.185.71.34
options edns0

# cat /var/unbound/forward.conf
# This file was generated by local-unbound-setup.
# Modifications will be overwritten.
forward-zone:
	name: .
	forward-addr: 216.185.71.33
	forward-addr: 216.185.71.34


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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
9 Brockley Drive              vox: +1 905 561 1241
Hamilton, Ontario             fax: +1 905 561 0757
Canada  L8E 3C3