Re: What can djbdns, (or any DNS Server/cacher) do for me? - from Sh4d03

From: William Ahern (william_at_wilbur.25thandClement.com)
Date: 11/30/04

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    Date: Mon, 29 Nov 2004 16:00:05 -0800

    Sh4d03 <sh4d03@tpg.com.au> wrote:
    > Thank you to both Mark and Peter,

    > However, there has been a little bit of a misunderstanding in what I
    > initially asked. As a result of what you've both said I believe I'll switch
    > to using BIND to start off with and then experiment with using DJBDNS.

    > What I was actually wanting was an understanding as to what 'type' of system
    > I should/would be setting up? Am I correct in assuming I should be setting
    > up a DNS cacher? Will that also handle all my DNS lookups if it doesn't know
    > the answer itself? What's the correct terminology for this. I've looked at a
    > few sites and docs etc but different people seem to be using different names
    > for the different systems - very confusing.

    The different DNS functions provided by a DNS server include caching,
    recursive resolution, and acting as an authority.

    Caching, of course, is just storing the results of a previous lookup. A
    caching nameserver is usually also a recursive nameserver (that is,
    recursively walking the authority chain to resolve some particular address),
    since you need something to cache. So, those two go hand-in-hand.

    Acting as an authority means that if you get a request for an address, you
    give back a response directly. You already know the answer, because you're
    the one that makes it up (or reads it from a config file--on disk or by
    asking a cooperating primary server).

    The authority and recursive functions are sometimes split because you might
    want a DNS server to host a domain name, but you're not particularly eager
    to do the leg work of recursive resolution of random domains for clients
    (which can generate a lot of traffic).

    Also, sometimes you only want to do recursive resolution for particular
    clients, for instance clients on your internal network. BIND 9 lets you
    specify these types of ACL's directly, rather than handling it from the
    network stack (e.g. by using PF).

    > Also, once setup - what benefits will this have for me? I realise that
    > having a DNS cache will help a dial-up user, how much speed increase will I
    > notice with a 128 DSL connection?

    Probably none. But it usually can't hurt, and would be a good learning
    experience.

    > Further than this desire to "setup a DNS server" - I need someone to advise
    > what 'type' of DNS "server/cacher" I will set up. Which would be in my best
    > interest/benefit?

    Use the stock BIND 9 in OpenBSD until you have a reason not to. You may
    never find such a reason. At the very least, keep a stock system until you
    understand it well enough to know what you're changing. I liken it to Legos.
    When I was a kid I'd always put together a new lego set by following the
    instructions first. I'd always tear it down afterwards, but I understood
    that I could make something cooler by first understanding how the pieces
    went together originally. If you just dumped the pieces on the floor and
    went to town willy-nilly, 9 times out of 10 what you created was junk, and
    you kept creating junk. You didn't really have a full idea of the
    possibilities until you knew what somebody else did beforehand.

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