DNS lookup fails occasionally on a Mac mini and a MacBook Air

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DNS lookup fails occasionally on a Mac mini and a MacBook Air

I have a home network with a number of computers connected, including a MacMini 2 and a new MacBook Air. There is a Unify USG router/firewall and this runs as the DNS server for the network. The USG is configured to resolve names for internal devices and forward queries for external computers to OpenDNS. The LAN's DHCP settings specify that the primary DNS server is the USG and OpenDNS is the secondary in case internal resolution fails.

Both Macs experience the following problem, but no other machines - implying this is a MacOS-specific problem and not a network problem. This is important as the symptoms could otherwise imply a failure of the USG's DNS server.

Occasionally, no apparent frequency, DNS name resolution fails for internal hosts. External hosts resolve OK.

Opening a terminal reveals that

dig host.local

works. It comes back with the correct IP address. However

ping host.local

fails because the name doesn't resolve. Ping'ing the IP address works of course.

Rebooting resolves the problem, as does switching to a different network location: even if it has the same settings.

Any thoughts on what might be causing this?

Mac mini, macOS 10.13

Posted on May 27, 2023 05:03 AM

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Answer 1

May 27, 2023 08:40 AM in response to Guff

Guff wrote:

I have a home network with a number of computers connected, including a MacMini 2 and a new MacBook Air. There is a Unify USG router/firewall and this runs as the DNS server for the network. The USG is configured to resolve names for internal devices and forward queries for external computers to OpenDNS. The LAN's DHCP settings specify that the primary DNS server is the USG and OpenDNS is the secondary in case internal resolution fails.

Both Macs experience the following problem, but no other machines - implying this is a MacOS-specific problem and not a network problem. This is important as the symptoms could otherwise imply a failure of the USG's DNS server.

Occasionally, no apparent frequency, DNS name resolution fails for internal hosts. External hosts resolve OK.

Opening a terminal reveals that

dig host.local

works. It comes back with the correct IP address. However

ping host.local

fails because the name doesn't resolve. Ping'ing the IP address works of course.

Rebooting resolves the problem, as does switching to a different network location: even if it has the same settings.

Any thoughts on what might be causing this?

see if there is anything helpful here—see Bob Harris:

https://discussions.apple.com/thread/254863233?answerId=259052611022#259052611022

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Answer 2

Guff Author

Level 1

10 points

May 30, 2023 11:00 AM in response to leroydouglas

Thanks, but I've already ruled out a DNS server issue - everything works OK on other computers, and simply changing to a different, but identical, location is sufficient to resolve the problem.

The root of the problem would appear to be somewhere in the MACOS network setup. I know that this has changed a lot over the years. It has been previously reported that in earlier versions of MACOS name resolution was handled differently depending on whether you were initiating the lookup from the command line or from a GUI app.

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DNS lookup fails occasionally on a Mac mini and a MacBook Air

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