How do I share an IP address for two domains?

I have two domains and I want both of them to point to the same web
server using the same IP address. One domain is called teachkids.us
and the other is b-matrix.org.

>From my understanding, it should be possible to use the same IP
address and then on the web server setup two virtual websites: one
site for teachkids.us and the other for b-matrix.org.

This should be possible because in the recent past I had multiple
domains using a shared IP address but each domain had its own website
on the same server. I suppose that the web server doesn't look at the
IP address but probably gets information about domain from the sender
and knows what site to access.

Unfortunately I cannot do this on someone elses system and am not sure
why.

If I ping teachkids.us, the IP address is 71.249.137.181
If I ping b-matrix.org, the IP address is 63.251.92.195 Why??

Both domains are registered at the same location and both use the same
DNS entries:

dns1.name-services.com
dns2.name-services.com
dns3.name-services.com
dns4.name-services.com
dns5.name-services.com

So where am I getting a different IP address for b-matrix.org from?
Where is this set?

If I use NSLookup and set the server to dns1.name-services.com and
then type in b-matrix.org, it shows the IP address as 69.25.142.3

I'm entirely confused. For b-matrix.org, I get 63.251.92.195 pinging,
then I get 69.25.142.3 using NSLookup. Why does NSLookup give me
something entirely different again? What do I have to do to get the IP
address for b-matrix.org to be 71.249.137.181?

Thanks for your help!

On 2007-05-09, Polaris431 <(E-Mail Removed)> wrote:
>>From my understanding, it should be possible to use the same IP
> address and then on the web server setup two virtual websites: one
> site for teachkids.us and the other for b-matrix.org.

Just point both domain to the same IP in the DNS and then configure
your web server for name-based virtual hosts.

> If I ping teachkids.us, the IP address is 71.249.137.181
> If I ping b-matrix.org, the IP address is 63.251.92.195 Why??

'cause you didn't configure it correctly.

> So where am I getting a different IP address for b-matrix.org from?

From the DNS

> Where is this set?

In the DNS.

> If I use NSLookup and set the server to dns1.name-services.com and
> then type in b-matrix.org, it shows the IP address as 69.25.142.3

Then one of the DNS is wrong.

> I'm entirely confused. For b-matrix.org, I get 63.251.92.195 pinging,
> then I get 69.25.142.3 using NSLookup. Why does NSLookup give me
> something entirely different again?

'cause NSlookup uses a different set of libraries and works in complete
different way from ping. Ping is *NOT* a way to test DNS.

Davide

--
Normally, machines behave, 'cause they know what's good for them. This
is the main way to tell servers apart from lusers. The lusers don't know
what's good for them. -- Graham Reed on alt.sysadmin.recovery

> 'cause NSlookup uses a different set of libraries and works in complete
> different way from ping. Ping is *NOT* a way to test DNS.
>

Are you saying that Ping does not indicate the true IP address and
NSLookup does?

On 2007-05-09, Polaris431 <(E-Mail Removed)> wrote:
>
> Are you saying that Ping does not indicate the true IP address and
> NSLookup does?

I am saying that Ping is not to be used for testing dns because is not
designed to do so. Ping doesn't use the same dns-libraries that nslookup
does, in fact, nslookup has the libraries built-in and is considered
obsolete for that reason. nslookup can return a complete different
result than any other network-related tool or software because of the
different implementation. A quick google search will tell you so.

Davide

--
All programs evolve until they can send email. -- Richard Letts
Except Microsoft Exchange. -- Art

Davide Bianchi wrote:

> On 2007-05-09, Polaris431 <(E-Mail Removed)> wrote:
>>
>> Are you saying that Ping does not indicate the true IP address and
>> NSLookup does?
>
> I am saying that Ping is not to be used for testing dns because is not
> designed to do so. Ping doesn't use the same dns-libraries that nslookup
> does, in fact, nslookup has the libraries built-in and is considered
> obsolete for that reason. nslookup can return a complete different
> result than any other network-related tool or software because of the
> different implementation. A quick google search will tell you so.
>
> Davide
>

I agree with the final conclusion, but there is a slight error in this:

GNU ping does not have name resolution libraries built in, but uses glibc's
gethostbyname() which, on GNU/linux at least uses libnss and can derive
it's source data from DNS, LDAP, NIS, files (/etc/hosts) or any number of
other places that someone cares to configure or write a plugin for in some
particular priority order.

nslookup of course interrogates the DNS servers, as does it's more modern
variant: dig

So, to support the point that Davide made, Polaris might want to try adding
this to his /etc/hosts:

10.0.0.1 www.ibm.com

and make sure that /etc/nsswitch.conf contains:

hosts: files dns

Try:

ping www.ibm.com
nslookup www.ibm.com

before and after.

Cheers

Tim

On Wed, 09 May 2007 06:16:29 -0700, Polaris431 wrote:

> I have two domains and I want both of them to point to the same web
> server using the same IP address. One domain is called teachkids.us
> and the other is b-matrix.org.
>
>>From my understanding, it should be possible to use the same IP
> address and then on the web server setup two virtual websites: one
> site for teachkids.us and the other for b-matrix.org.
>
> This should be possible because in the recent past I had multiple
> domains using a shared IP address but each domain had its own website
> on the same server. I suppose that the web server doesn't look at the
> IP address but probably gets information about domain from the sender
> and knows what site to access.
>
> Unfortunately I cannot do this on someone elses system and am not sure
> why.
>
> If I ping teachkids.us, the IP address is 71.249.137.181
> If I ping b-matrix.org, the IP address is 63.251.92.195 Why??
>
> Both domains are registered at the same location and both use the same
> DNS entries:
>
> dns1.name-services.com
> dns2.name-services.com
> dns3.name-services.com
> dns4.name-services.com
> dns5.name-services.com
>
> So where am I getting a different IP address for b-matrix.org from?
> Where is this set?
>
> If I use NSLookup and set the server to dns1.name-services.com and
> then type in b-matrix.org, it shows the IP address as 69.25.142.3
>
> I'm entirely confused. For b-matrix.org, I get 63.251.92.195 pinging,
> then I get 69.25.142.3 using NSLookup. Why does NSLookup give me
> something entirely different again? What do I have to do to get the IP
> address for b-matrix.org to be 71.249.137.181?
>
> Thanks for your help!

You need to contact name-services.com, and ask them to set the right DNS
entries. (A records)

repo@cannabis:~$ nslookup b-matrix.org
Server: 127.0.0.1
Address: 127.0.0.1#53
Non-authoritative answer:
Name: b-matrix.org
Address: 63.251.92.195
repo@cannabis:~$

repo@cannabis:~$ nslookup teachkids.us
Server: 127.0.0.1
Address: 127.0.0.1#53
Non-authoritative answer:
Name: teachkids.us
Address: 71.249.137.181
repo@cannabis:~$



--
Chaos, panic & disorder - my work here is done
http://beginnerslinux.org

Polaris431 <(E-Mail Removed)> wrote:
>>From my understanding, it should be possible to use the same IP
> address and then on the web server setup two virtual websites: one
> site for teachkids.us and the other for b-matrix.org.

Yep. This is called "virtual hosting" and is a standard feature of web
servers such as apache.


> If I ping teachkids.us, the IP address is 71.249.137.181
> If I ping b-matrix.org, the IP address is 63.251.92.195 Why??

Your DNS provider is providing duff information:

$ dig +short b-matrix.org @dns1.name-services.com
69.25.142.3
$ dig +short b-matrix.org @dns2.name-services.com
216.52.184.240
$ dig +short b-matrix.org @dns3.name-services.com
63.251.92.195
$ dig +short b-matrix.org @dns4.name-services.com
64.74.96.243
$ dig +short b-matrix.org @dns5.name-services.com
64.74.96.243

All of those should have been the same value - unless you've deliberately
set up multiple A records for your domain.


While we're here, the SOA shows a strangely lov value (typically but
not necessarily it's usually YYYYMMDDNN, where NN is a sequence value
for changes on that day), but worryingly it's the same for all five
DNS servers:

$ for N in `seq 5`; do dig +short soa b-matrix.org @dns$N.name-services.com; done
dns1.name-services.com. info.name-services.com. 2002050701 10001 1801 604801 181
dns1.name-services.com. info.name-services.com. 2002050701 10001 1801 604801 181
dns1.name-services.com. info.name-services.com. 2002050701 10001 1801 604801 181
dns1.name-services.com. info.name-services.com. 2002050701 10001 1801 604801 181
dns1.name-services.com. info.name-services.com. 2002050701 10001 1801 604801 181

You did increment the SOA serial number when you changed the zone
information, didn't you...?

Chris