DNS problems this morning -

[Tim]

Tim:
> > Configure the other computers on your LAN to use the DNS server
> > computer's IP address as their DNS server.  It's as simple as that.

Bob Goodwin:
> Will dns look-ups from the other computers be added to the
> nameserver list?

You appear to have the wrong end of the stick.

When any client on your LAN asks your DNS server for an address, the DNS
server makes a query to external DNS servers, caches the results, and
tells your client the answer.  The next client on your LAN to ask about
the same address, will be told the cached answer.

Telling your clients which DNS server to use is another matter.

> What if my computer is shut down for the night, will the others go
> on and use the ISP dns?

If you had, say your DNS server at 192.168.0.1, and clients configured
to only use 192.168.0.1 as their DNS server, then they're reliant on
192.168.0.1 always being there.

If you had configured your clients with a list of DNS servers, they'll
query one of them, only trying other ones when they don't get any
response.  I don't know what determines which DNS server will get
queried out of a list, whether Fedora will do it sequentially down the
list, or randomly.  Nor whether any subsequent queries will use the same
server as the last time, or pick another one each time.


> > The complications are:  If your other computers are assigned addresses
> > by DHCP, then you have to put overrides on the individual client
> > configuration, or configure the DHCP server to say that *YOUR* DNS
> > server is the LAN's DNS server to all computers that ask it for an
> > address (I do this with mine).

> DHCP via the router was the path of least resistance, they get
> static assignments, but I could set them up with fixed addresses if
> that is necessary. I used to do that but the present set-up is
> easier to implement and normally works perfectly.

They don't need to be fixed, your DNS server will not care what IP they
have today, or tomorrow.  My LAN has a mixture of clients with fixed and
dynamic addresses, some are fixed by hand configuring those machine's
network configuration, on those machines.  Others are fixed by
configuring the DHCP server to always give the same IPs to the same
machines.

In any case, they all use the same DNS server.  The manually configured
machines had the local DNS server manually set in their config.  All the
rest were told to use the local DNS server in the data that the local
DHCP server gives out.

-- 
[tim at localhost ~]$ uname -rsvp
Linux 3.6.6-1.fc17.x86_64 #1 SMP Mon Nov 5 21:59:35 UTC 2012 x86_64

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