[Cialug] DNS and playing well with OSX

[Matt Stanton]

In that SOA record response, the master nameserver for your domain is listed as ns75.domaincontrol.net.  Are you using a real domain name inside your LAN, and trying to assign reserved internal LAN IP addresses to the subdomains (A records)?  Like trying to assign 10.0.1.5 as an A record for CentOS1.somerealdomain.com?  That is, are you trying to use some subdomains with "real" public server IPs and other subdomains with LAN server IPs, or are you just trying to create a fake domain only for use on your LAN?

If you are just creating a fake domain for use only on your LAN, then you need to use whatever hostname you have given to your Mac as the master nameserver in the SOA record.  You also need to specify the nameserver again in an NS record, I believe, then you need your address records and, optionally, some CNAME records:

myLANdomain.net. IN SOA OSXSLS1.myLANdomain.net john.myLANdomain.net (
              1         ; Serial
              3h       ; Refresh after 3 hours
              1h       ; Retry after 1 hour
              1w       ; Expire after 1 week
              1h )     ; Negative caching TTL of 1 day

myLANdomain.net. IN NS OSXSLS1.myLANdomain.net.

Gateway.myLANdomain.net. IN A 10.0.1.1
OSXSLS1.myLANdomain.net. IN A 10.0.1.2
CentOS1.myLANdomain.net. IN A 10.0.1.5

www.myLANdomain.net. IN CNAME CentOS1.myLANdomain.net.
ftp.myLANdomain.net. IN CNAME CentOS1.myLANdomain.net.
mail.myLANdomain.net. IN CNAME CentOS1.myLANdomain.net.

You can also go through the whole LAN and assign PTR records so that looking up an IP address will tell you what the domain name record for that address is.  It's a lot of extra work, and not really needed, but if you have already assigned a static IP to every computer on your LAN and given each computer a subdomain, having things point the opposite direction might help you if you see a particular IP address doing something funky on the network by allowing you to see what the "name" of the computer is.

I created my own TLD on my LAN and assigned every computer a name and even set up PTR records so DNS resolves in both directions.  I did it more as a learning experience and so that I could run Zimbra Collaboration Suite on my LAN (it's neat having your own email/task list/calendaring system for your family to use at home).  There are a lot of real annoyances doing this can cause, mainly involving making sure the computer running DNS for your LAN is always up and running smoothly so that the internet functions properly for everyone in the house.

-- Matt (N0BOX)

P.S. - If you've already done all this and set it up basically the same way, then I'm sorry for going so in-depth, but without being able to actually look at the configuration of your home network and the nameserver records it's hard to make suggestions.  :(

Sent from my ASUS Transformer

-----Original Message-----
From: Moder John II Lee <jmoder at me.com>
To: cialug at cialug.org
Sent: Thu, 19 Sep 2013 7:26 PM
Subject: [Cialug] DNS and playing well with OSX

Hello--  I am a new subscriber here, and was hoping to learn some about a new Linux install, and fix an initial problem I am having.  

II am a Linux/CentOS newbie, and am not overly technical to begin with so I beg mercy from all the super users here! 

I currently have an OSX Snow Lepord Server running my home office. Wanted to try Linux, with eventual plans to use it as a second server to eventually serve a Domino/Lotus Notes application, and a pseudo share point server.  I would like it to authenticate to the OSX domain, but first I think I need to solve this problem before jumping to that one.  

My question is: Why can't I Ping by hostname from the OSX box to the CentOS box? 

The OSX box is doing DNS for the network. The CentOS box is pointed to that DNS server. I have a Machine Record in the Server's DNS pointing to the correct IP. 

I have already checked the Hosts file, which only has loopback addresses. 

I have also checked the resolv.conf file, which again does not contain anything out of the ordinary. 

I can ping the CentOS box from the OSX box by IP, just not my name.

As for current IP Scheme, here is what I have:

Router at 10.0.1.1
OSXSLS1 at 10.0.1.2 set static, DNS pointing to loopback and externals.
CentOS1 at 10.0.1.5 set static and DNS pointing to 10.01.2.

When I do dig from OSXSLS1 this is what I get:


OSXSLS1:~ administrator$ dig Centos1.(mydomain).net

; <<>> DiG 9.6-ESV-R4-P3 <<>> Centos1.(mydomain).net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 12101
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;Centos1.mydomain.net.	IN	A

;; AUTHORITY SECTION:
(mydomain).net.	2463	IN	SOA	ns75.domaincontrol.com. dns.jomax.net. 2013091200 28800 7200 604800 600

;; Query time: 29 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Sep 19 19:17:50 2013
;; MSG SIZE  rcvd: 109

I have tried to add it to the hosts file, and it works as expected, but I would rather figure out why it is not responding correctly through DNS.

Suggestions? 


Thanks!

John




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