December 25, 2019

hardcoded DNS will bite you in the ass in the most subtle and annoying ways

tl;dr - make a list of all of the annoying places where you need to hardcode DNS entries. you’ll thank yourself later.

i retired a DNS server this past week. couple that with the expiration of a couple of guest wifi passes and i discovered that there’s a hidden DNS setting on the APs that can make captive portal DNS resolution miserable if the DNS server is offline.

on ubiquit APs the preferred DNS server in the AP is what’s used for the resolution of DNS for the hotspots. it doesn’t appear to attempt to use the alternate DNS server to trigger / enable resolution. even if that address is in the preferred (pre-auth) networks list.

note also, that while you might only log into your synology nas a couple of times a year. it needs to get refreshed DNS server settings …

home networking devices with hardcoded DNS shiz

  • ubiquity APs - make sure that the preferred DNS is always reachable.
  • synology NAS - services will just start to silently fail with no debugging info.
  • that docker container you start with the --dns flag to override the stock resolution. because there’s always one …

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