> On Fri, 18 Aug 2017, Dan wrote: >> Every day, just after midday, I suddenly lose access to DNS name >> resolution, and therefore become unable to interact with any remote >> hosts, even though my network interface is still up. On Fri, 18 Aug 2017, Howard, Chris wrote: > Do you think it might have something to do with your DHCP lease > expiring? Thanks, Chris, but it doesn't look like it. On Friday (August 18th), the failure of name resolution happened between 12:25 and 12:30. In /var/log/messages, I find the following entries apparently relevant to when DHCP leases were due to expire: Aug 18 12:00:47 shepherd rsyslogd: [origin software="rsyslogd" swVersion="7.4.7" x-pid="1100" x-info="http://www.rsyslog.com"] start ... Aug 18 12:00:53 shepherd dnsmasq-dhcp[2445]: DHCP, IP range 192.168.122.2 -- 192.168.122.254, lease time 1h ... Aug 18 12:01:03 shepherd NetworkManager[1019]: <info> [1503054063.6017] dhcp4 (wlp2s0): lease time 86400 ... Aug 18 12:01:03 shepherd dhclient[2380]: bound to 10.188.20.97 -- renewal in 39007 seconds I think the first symptom of the loss of name resolution is probably represented by this entry: Aug 18 12:29:54 shepherd firefox.desktop: 1503055794168#011addons.update-checker#011WARN#011Update manifest for [log in to unmask] did not contain an updates property You'll note that all this has been happening on a wireless interface (wlp2s0) - my employer's wi-fi network. Yesterday in the crucial period between midday and 1pm, I was connected to my employer's wired ethernet network instead, and the problem didn't arise. I'll go wireless again for the relevant period today, and if I lose name resolution, I'll try Andrew's ping -n suggestion for further diagnostic data. -- Thanks, Dan