Date: Fri, 28 Mar 2003 11:20:34 +1030 From: Greg 'groggy' Lehey <grog@FreeBSD.org> To: James Earl <mtntrip@telus.net>, Jaime <jaime@snowmoon.com>, James Earl <jdearl@telus.net> Cc: freebsd-questions@freebsd.org Subject: Re: Reverse DNS and single IP address space Message-ID: <20030328005034.GA72254@wantadilla.lemis.com> In-Reply-To: <20030327214336.GE645@comp4.ici.net> <20030327135506.A60255-100000@malkav.snowmoon.com> <20030327185204.GA645@comp4.ici.net> <20030327183154.GA622@comp4.ici.net> References: <20030327183154.GA622@comp4.ici.net> <20030327103827.A8705@mail.telestream.com> <20030327185204.GA645@comp4.ici.net> <20030327214336.GE645@comp4.ici.net> <20030327185204.GA645@comp4.ici.net> <20030327135506.A60255-100000@malkav.snowmoon.com> <20030327183154.GA622@comp4.ici.net> <20030327103827.A8705@mail.telestream.com> <20030327185204.GA645@comp4.ici.net> <20030327183154.GA622@comp4.ici.net>
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On Thursday, 27 March 2003 at 11:31:54 -0700, James Earl wrote:
> I'm in the process of setting up primary and secondary name servers.
> This is my first time setting up named so I'm kinda a newbie in this
> area.
>
> My question is in regards to in-addr.arpa entries in named.conf and
> zone files. In the FreeBSD Handbook and alot of other resources, I've
> noticed how the ip address is reversed, with part of the address left
> off. For example:
>
> zone "0.168.192.in-addr.arpa" {
> type slave;
> file "s/0.168.192.in-addr.arpa.bak";
> masters {
> 192.168.1.1;
> };
> };
This is a slave entry. It would be more interesting to see what the
master config looks like. Anyway, this address is in an RFC 1918
non-routable address range. That means it's not unique, and it's
completely meaningless on the global Internet. In fact, I have that
address here :-)
$ nslookup 192.168.0.1
Server: echunga.lemis.com
Address: 192.109.197.82
Name: phantom.hidden.lemis.com
Address: 192.168.0.1
> Now, what happens when I have only been allocated a single ip address
> from my ISP (well, actually two, one for the primary/master and one for
> the secondary/slave)?
in-addr.arpa. addresses come in blocks of 256. You don't get the
choice, your ISP has to provide reverse DNS. If he refuses, your only
options are to find a new ISP or a /24 address range for which you can
get reverse lookup.
On Thursday, 27 March 2003 at 11:52:04 -0700, James Earl wrote:
> On 2003.03.27 11:38 Victor Bondarenko wrote:
>> On Thu, Mar 27, 2003 at 11:31:54AM -0700, James Earl wrote:
>> [...]
>>> Or, do I even need to worry about reverse DNS entries since my ISP
>>> already has them setup?
>>
>> If your ISP has reverse DNS for your IP(s), there's really no point in
>> you mapping them on your own. Your network might see whatever you've
>> mapped, but the rest of the world will see what your ISP maps.
>
> I'm assuming if I can use nslookup [ip-address] to get my hostname,
> that reverse DNS on the ISP is setup properly. Is this an okay
> assumption?
No. It depends on the name server you ask. If you have set up your
name server as above, you'll get a response. Nobody else will, for
the reasons mentioned above.
On Thursday, 27 March 2003 at 13:55:37 -0500, Jaime wrote:
>> I'm assuming if I can use nslookup [ip-address] to get my hostname,
>> that reverse DNS on the ISP is setup properly. Is this an okay
>> assumption?
>
> If you know enough about nslookup, then yes. I'd suggest "host
> -v 1.2.3.4", though. Its a bit easier. :)
Is that easier than "nslookup 1.2.3.4"?
On Thursday, 27 March 2003 at 14:43:36 -0700, James Earl wrote:
> Thanks for the help everyone! From your suggestions, it appears
> reverse DNS is setup properly. Now if only my ISP could provide as
> good of support, as all of you provided me! :)
Unfortunately, most of it was wrong :-(
Greg
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