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Re: [LUG] Dual DHCP/DNS

 

Simon Waters wrote:
> Simon Williams wrote:
>> I can't turn off the DHCP and DNS server on the router, because at any 
>> given point in time I might break my server, and the rest of my family 
>> needs internet access.
> 
> If it isn't on 24x7 it might not make much sense to run Postfix on it,
> but guess that depends what Postfix is used for.

Postfix is used mainly for internal and outgoing mail. All incoming mail 
goes via a dropbox and is downloaded with fetchmail.

>> This is fine, except that the DNS server on the router is a bit broken 
>> and postfix doesn't like it.
> 
> Define broken.
> 
> Postfix will work with standards compliant DNS servers.

It's not specifically postfix, it was something to do with my router and 
email specific DNS lookups (probably MX records).

It's in an email you sent, but I can't for the life of me find it. Gmail 
can't find it either, which probably means it never existed ;)

Original message is here:
http://www.dclug.org.uk/archive/2007/07/msg00556.html

>> So my server has to use it's own DNS. Which 
>> leads to a problem. The hostnames which get added dynamically by the 
>> router do not show up on the server.
>>
>> This leaves a few possible solutions:
>> 1. Somehow convince the router to update the server's DNS with dynamic 
>> leases (I don't think this is possible).
> 
> Maybe possible but hard work.
> 
>> 2. Turn on both the server's and the router's DHCP servers, but make the 
>> servers DHCP override the router's if it's available.
> 
> Sounds very messy.

Probably. But really there should be a precedence option for DHCP. We 
have master/slave servers for smb, and primary/secondary servers for 
DNS. Why can't I do that with DHCP?

>> 3. Tell the server to use the router's DNS, but for local queries only.
> 
> If the router puts local DNS entries in a specific zone (or zones -
> think forward and reverse lookup), you can forward queries for that zone
> on the server.
> 
>> Anyone know how to do any of the above, or even if they are possible?
> 
> Why does the server need the local names resolved?
> 
> Could you use static IP addresses allocated using the routers DHCP
> service. Then just put static entries for those in the servers config
> (hosts file or DNS which ever is easiest).
> 
> Most of our Linux servers get along just fine with no idea who the
> Windows clients are. Where it matters we do it statically, but that is
> usually a box offering a service on Windows, and so we ensure it has a
> static IP address.

I often log into other machines or need to smb files from them when 
logged into my server remotely. And it helps to know who's who.

I could statically assign everything I guess.

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