Ping by Name — Unknown Host

Some time after manually restoring the local router, I realized I had not tested the guest wireless network connection.

The laptop connected to the guest connection, but a ping test to the local ISP web site failed with the infamous unknown host error message. Other ping tests succeeded.

Typically that error message means DNS is configured incorrectly, commonly with /etc/resolv.conf. In this case the guest wireless network connection is enabled through NetworkManager and DNS resolution is automatic through the router DHCP server.

Why were ping tests succeeding except with that single domain name?

A ping test to the actual IP address succeeded and that provided a clue.

I discovered the respective entry in /etc/hosts had a trailing inline comment that was not actually commented out with the # symbol. From a lookup perspective the domain name was malformed and the lookup failed.

That file is copied from the office desktop to the router through a daily cron job.

Fixing the malformed comment resolved the problem with the guest network.

Except a ping test of the same domain name when connected to the normal house network subnet did not result in any such error. The ping test succeeded.

I do not know why. One guess is Yet Another Anomaly in the DD-WRT firmware or related BusyBox software.

Posted: Category: Usability Tagged: General

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