Is more than one A record per IP OK?

[Bobk]

Archived from groups: microsoft.public.win2000.dns (More info?)

Is it OK to have two or more A records pointing to the same IP address? For
example if I have a web server with one IP address. And I want people to
find it whether they use www.bobweb.myco.com or www.sallyweb.myco.com, can I
add both names AS A RECORDS on my ISP's DNS server like this?

www.bobweb.myco.com. IN A 100.100.100.1
www.sallyweb.myco.com. IN A 100.100.100.1


I understand that it's supposed to be done with a CNAME. I just want to
know what (if any) problem this would cause.


Thanks!

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

It is ok to have two or more A records pointing to the same IP address. You
should be aware of some issues that could come up with sendmail (if you are
using that) and some other applications by doing this. Given what you are
doing (which appears to be all website references) then you will be fine.

If you want to find out more information see pages 56-58 of "DNS and BIND"
2nd ed. by Albitz and Liu (O'Reilly Press). I think the current edition is
4 or something but I haven't bought the newest edition yet. You can find
the book here:
http://www.oreilly.com/catalog/dns4/index.html

Regards,
Ed Horley
Microsoft MVP Server - Networking

"bobk" <bkreimborg@netzero.com> wrote in message
news:eMuGMFjYFHA.1412@TK2MSFTNGP12.phx.gbl...
> Is it OK to have two or more A records pointing to the same IP address?
> For example if I have a web server with one IP address. And I want people
> to find it whether they use www.bobweb.myco.com or www.sallyweb.myco.com,
> can I add both names AS A RECORDS on my ISP's DNS server like this?
>
> www.bobweb.myco.com. IN A 100.100.100.1
> www.sallyweb.myco.com. IN A 100.100.100.1
>
>
> I understand that it's supposed to be done with a CNAME. I just want to
> know what (if any) problem this would cause.
>
>
> Thanks!
>
>
>

 

[Guest]

Archived from groups: microsoft.public.win2000.dns (More info?)

"bobk" <bkreimborg@netzero.com> wrote in message
news:eMuGMFjYFHA.1412@TK2MSFTNGP12.phx.gbl...
> Is it OK to have two or more A records pointing to the same IP address?
For
> example if I have a web server with one IP address. And I want people to
> find it whether they use www.bobweb.myco.com or www.sallyweb.myco.com, can
I
> add both names AS A RECORDS on my ISP's DNS server like this?

Absolutely.

This is not only allowed but also normal practice.

> www.bobweb.myco.com. IN A 100.100.100.1
> www.sallyweb.myco.com. IN A 100.100.100.1

Alternatively the second name can be specified as a CNAME.

> I understand that it's supposed to be done with a CNAME. I just want to
> know what (if any) problem this would cause.

There is no real "supposed to" here; you may do it either
way (usually) but the A record always works.

Only disadvantage is if you change the address you must
change all of the A records manually.

As to the web server these will refer to the same content
but you MAY if you choose define different virtual "sites"
based on these differing names. Such is called a "host header"
within a web server configuration.


--
Herb Martin, MCSE, MVP
Accelerated MCSE
http://www.LearnQuick.Com
[phone number on web site]