:: Re: [DNG] how to clear DNS cache
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Skribent: Simon Hobson
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Til: dng@lists.dyne.org
Emne: Re: [DNG] how to clear DNS cache
Hendrik Boom <hendrik@???> wrote:

> Don't several system comopnents, such as dhcp clients, happily rewrite
> resolve.conf, wiping out anything the sysadmin may have set up.


Yes, but if you are using DHCP to configure your interfaces, there's an implicit assumption that you want "stuff" configured by a service on the network you connect to. In most cases, I would suggest that's a reasonable thing - but as mentioned, you can over-ride that if you want to.
I have actually had to do that in the past - though IIRC I configured the DHCP client to not configure DNS. I was using an ADSL modem that only worked if the router behind it used DHCP to get the public IP associated with the PPPoA session. As it happens I had a static IP, but still had to run DHCP on that interface to keep the modem happy - but I was running my own local resolver (as well as split-horizon DNS) so didn't want the resolver settings changing to point to the ISP.

What's the next logical fallback the systemd guys will do - shall we run a book ? Just a bit of fun.
My 2d for kicks ...
The logical extension of that resolvd fallback would be for interfaces to be auto configured. If you get no answer from a DHCP server, then lets look at network traffic and guess what the local subnet is - or heck, it's more than likely 192.168.1.0/24. So lets just pick an address, check that it's not already in use, then try 192.168.1.1 and 192.168.1.254 for a router. Great, that's connectivity sorted on broken networks - lets bury it where no-one can see this in any config file :-)