I can answer half of your questions with experience and interpret other
articles for the rest.



-----Jim Van Meggelen <[email protected]> wrote: -----

>I'm hoping to learn a bit more about DNS.
>
>I get it in theoretical terms, but the devil is in the details.
>
>Let's say I have my website atwww.mycompany.com
>
>The MX record points to my email provider somehow, and that seems to
>be
>easy enough to set up.
>
>But how about having SIP calls to go to my PBX (which may or may not
>have
>a hostname)?
>
>There are a few things that I can't quite get the hang of:
>
>1. should I give my PBX a hostname such as pbx.mycompany.com?

I would say normally a host name is desired. IPV4 is easy enough to
remember, but when IPv6 comes around good luck trying to remember that
number.

>2. should I make that a zone, and run a DNS server on my PBX?

You could, but I don't think it's needed.

>3. how do I getsip:[email protected]  to go
>tosip:[email protected]?

Reading says that you would create a DNS record like the following in your
mycompany.com zone:

_sip._udp      SRV 0 5060 pbx.mycompany.com.

And you would need an address record:

pbx    A 1.2.3.4

>4. should I just have the main DNS handle sip requests with the IP
>address of my PBX, and forget about the zone/server
>pbx.mycompany.com?

I've only done cursory reading on SRV records, but it looks like it will
only take a host name.

>5. should I be giving all my devices a hostname? do I allow those
>hostnames to be handled by DNS? what about NAT and security?

We generally use DNS for all hostnames. The reason is convenience, but it
also makes a good authoritative reference of used IP addresses. We use
reverse zones (in-addr.arpa zones) for this. These zones map IP addresses
to host names.

We also create service names, for example: we might create an
smtp.mycompany.com and a pop.mycompany.com even though they are the same
system and IP address, just in case we separate them in the future.

BIND (and probably other DNSes) support split horizon DNS. We do this at
the office. Queries from local network hosts get difference results than
foreign hosts. That way we can hide hosts from external view entirely or
offer external addresses. When we configure client software on our laptops
we use names rather than IPs so that it works seamlessly in or out of the
office.

>I'm not looking for answers to all this in an email per se, but more
>asking if somebody is willing to do a talk for us that might help
>demystify all this?

Too late.I might be able to talk depending on the date. I'm not an in-depth
expert, but I've been administering  DNS servers for 15 years for as many
as 100 zones.

>BTW, even though I am clearly not qualified to speak on this topic,
>I'm
>a pretty quick study, I have experience with both speaking and
>training,
>and so would be more than willing to do some of the grunt work and
>presentation work necessary to present this to the group, if that
>helps
>any of you who have the know-how, but perhaps aren't comfortable
>speaking to an audience.


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