Question on DNS setup change not working.

[Michael D. Setzer II]

Our MIS department just decided to not allow the use of the public 
IP addresses of system from local machines, so I made the 
additions to the hosts file with the private ip and the name.
restart named and restarted squid, and squid picked up the 
change, and would bring up pages using the name. Unfortunately, 
dig and other options would still be using the public IP instead.

Tried restarting the machine to see if something might not have 
been changed, but it remains the same.

In the past, I had done this same thing for local services I have.
redhatgcc.dyndns.org has a public ip of 202.128.73.24, but on the 
inside it has the private ip of 192.168.50.41. So, the hosts file has 
the link between the 192.168.50.41 and the 
redhatgcc.dyndns.org,  and it reports that.

But now the college web sever that has a public IP of 
202.128.72.2 is now mapped internally to 10.10.10.11, so I added 
the same mapping but dig still reports the 202.128.72.2 number, 
and that will no longer work from the inside?

Is there something that might be caching the old information even 
after a system restart?  

At this point to get it to work, I've had to point to there DNS server 
that using 172.16.0.4? We've got less than 1000 machine on 
campus, but they now have 10.x.x.x networks, and 172.16.x 
networks and a number of 192.168.x networks...


+----------------------------------------------------------+
  Michael D. Setzer II -  Computer Science Instructor      
  Guam Community College  Computer Center                  
  mailto:[e-mail]                            
  mailto:[e-mail]
  http://www.guam.net/home/mikes
  Guam - Where America's Day Begins                        
  G4L Disk Imaging Project maintainer 
  http://sourceforge.net/projects/g4l/
+----------------------------------------------------------+

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[Tim]

On Sat, 2011-09-03 at 11:36 +1000, Michael D. Setzer II wrote:
>  I was under the impression that the resolv.conf 
>  with hosts bind was also for dns. 
resolv.conf is used to tell your network the address of a DNS server,
and it can list the domain names to be added to hostnames, for
abbreviated queries.

i.e. "ping printserver" can become "ping printerserver.example.com"

The hosts file is used by anything which can use the hosts data to
resolve a name.  e.g. Your web browser.

The BIND DNS server uses its own configuration files to give answers to
queries.  In general, it looks for its own DNS record files, then
queries external (to itself) DNS servers.  The hosts file isn't part of
its workings.  There are other (simple) DNS servers which can look at
the hosts file for resolving addresses.

Amongst other things, the /etc/nsswitch.conf file lists how various
things will resolve queries.  Such as your web browser's query for a
domain may get resolved by first looking in the hosts file, then trying
a DNS server.  The "hosts:" line will configure how names are generally
resolved, there are other configuration lines to choose how other things
do their look-ups.

Squid has its own resolver tool, and I can't recall how it normally
works, but I'd be surprised if you can't configure how it goes about it.

It shouldn't be necessary to play around with restarting networks, or
rebooting, for a change in your hosts file to be noticed.  However,
certain applications may need restarting.  For instance, if you'd used
Firefox to browse www.example.com, the IP would have been looked up at
the time, and the answer will be held onto for the session.  So, changes
to the IP won't get noticed, during that time.

-- 
[tim@localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.

[Jatin K]

On Saturday 03 September 2011 12:26 AM, Michael D. Setzer II wrote:
>  Our MIS department just decided to not allow the use of the public
>  IP addresses of system from local machines, so I made the
>  additions to the hosts file with the private ip and the name.
>  restart named and restarted squid, and squid picked up the
>  change, and would bring up pages using the name. Unfortunately,
>  dig and other options would still be using the public IP instead.
>
>  Tried restarting the machine to see if something might not have
>  been changed, but it remains the same.
>
>  In the past, I had done this same thing for local services I have.
>  redhatgcc.dyndns.org has a public ip of 202.128.73.24, but on the
>  inside it has the private ip of 192.168.50.41. So, the hosts file has
>  the link between the 192.168.50.41 and the
>  redhatgcc.dyndns.org,  and it reports that. 
You need to setup a DNS server or add a new zone to existing DNS server 
for local network.
BTW /etc/hosts is not part of DNS , thats why you cannot see the effects 
during dig <name> command

Warm Regards

-- 
   °v°
  /(_)\
   ^ ^  Jatin Khatri
RHCSA,RHCE,CCNA
Registerd Linux user No #501175
www.counter.li.org
No M$

[Cameron Simpson]

On 03Sep2011 04:56, Michael D. Setzer II <mikes(a)kuentos.guam.net&gt; wrote:
| Our MIS department just decided to not allow the use of the public 
| IP addresses of system from local machines, so I made the 
| additions to the hosts file with the private ip and the name.
| restart named and restarted squid, and squid picked up the 
| change, and would bring up pages using the name. Unfortunately, 
| dig and other options would still be using the public IP instead.
| 
| Tried restarting the machine to see if something might not have 
| been changed, but it remains the same.

/etc/hosts is not part of DNS. It is part of the name lookup procedure
used by gethostbyname(). So: squid is affected by /etc/hosts, but dig
and named are NOT, and will not be: they are specificly DNS tools.

My recommendation is to add a special .local zone to your named with
names host1.local etc with the private addresses. Then add local to the
_front_ of the search path in /etc/resolv.conf:

  search local your.normal.domain.here

Then using the short names should work.

Cheers,
-- 
Cameron Simpson <cs(a)zip.com.au&gt; DoD#743
http://www.cskk.ezoshosting.com/cs/

"He deserves death!"
"Deserves it!  I daresay he does.  And many die that deserve life.  Is it in
 your power to give it to them?  Then do not be so quick to deal out death in
 judgement, for even the very wise may not see all ends."
        - Gandalf, _The Lord of the Rings_

[Michael D. Setzer II]

On 3 Sep 2011 at 7:47, Cameron Simpson wrote:

Date sent:      	Sat, 3 Sep 2011 07:47:02 +1000
From:           	Cameron Simpson <cs(a)zip.com.au&gt;
To:             	Community support for Fedora users 
<users(a)lists.fedoraproject.org&gt;
Subject:        	Re: Question on DNS setup change not working.
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>  On 03Sep2011 04:56, Michael D. Setzer II
> <mikes(a)kuentos.guam.net&gt; wrote:
>  | Our MIS department just decided to not allow the use of the public 
>  | IP addresses of system from local machines, so I made the 
>  | additions to the hosts file with the private ip and the name.
>  | restart named and restarted squid, and squid picked up the 
>  | change, and would bring up pages using the name. Unfortunately, 
>  | dig and other options would still be using the public IP instead.
>  | 
>  | Tried restarting the machine to see if something might not have 
>  | been changed, but it remains the same.
>  
>  /etc/hosts is not part of DNS. It is part of the name lookup procedure
>  used by gethostbyname(). So: squid is affected by /etc/hosts, but dig
>  and named are NOT, and will not be: they are specificly DNS tools.
>  
>  My recommendation is to add a special .local zone to your named with
>  names host1.local etc with the private addresses. Then add local to the
>  _front_ of the search path in /etc/resolv.conf:
>  
>    search local your.normal.domain.here
>  
>  Then using the short names should work.
>   
Thanks for the information. At the moment, the system is just 
running a caching nameserver, so will have to look at the process 
to setup the dns. I was under the impression that the resolv.conf 
with hosts bind was also for dns.

>  Cheers,
>  -- 
>  Cameron Simpson <cs(a)zip.com.au&gt; DoD#743
>  http://www.cskk.ezoshosting.com/cs/
>  
>  "He deserves death!"
>  "Deserves it!  I daresay he does.  And many die that deserve life.  Is it in
>   your power to give it to them?  Then do not be so quick to deal out death in
>   judgement, for even the very wise may not see all ends."
>          - Gandalf, _The Lord of the Rings_
>  -- 
>  users mailing list
>  users(a)lists.fedoraproject.org
>  To unsubscribe or change subscription options:
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+----------------------------------------------------------+
  Michael D. Setzer II -  Computer Science Instructor      
  Guam Community College  Computer Center                  
  mailto:[e-mail]                            
  mailto:[e-mail]
  http://www.guam.net/home/mikes
  Guam - Where America's Day Begins                        
  G4L Disk Imaging Project maintainer 
  http://sourceforge.net/projects/g4l/
+----------------------------------------------------------+

http://setiathome.berkeley.edu (Original)
Number of Seti Units Returned:  19,471
Processing time:  32 years, 290 days, 12 hours, 58 minutes
(Total Hours: 287,489)

BOINC@HOME CREDITS
SETI        11189934.576302   |   EINSTEIN     6468781.769851
ROSETTA      3563786.501816   |   ABC          7853564.918328