In Sean <
[email protected]> posted a question
Then Kevin replied below:
: Sorry the post subject was supposed to say Shadow DNS
:
:
::
:: Hi
::
:: Can someone explain in basic terms what shadow DNS is and when it is
:: used or point me to some info please.
::
:: Sean
There are a lot of terms used for this, shadow DNS, split DNS, Split horizon
DNS and more.
Basically it all comes back to the same thing. If you have a Public Domain
and a Private Domain of the same name. The DNS servers for these two
'namespaces' are Authoritative over their particular namespace.
One is public with public address, the other is private with private
addresses, neither knows of the others existence nor should they except by
delegation of particular records in it own namespace.
For instance let's use example.com for our name.
The public nameserver is authoritative over example.com for every one on the
internet, it holds ONLY records with publicly routable IP addresses, NEVER
put a record with a private address in a public zone, it WON"T work. But for
the sake of discussion you have a website hosted by your ISP named
www.example .com. So in the public DNS server you have a record named www
with the IP address of the website like this:
Name Type Data
www A <publicipaddress>
Now you have a Private domain also named example.com and it DNS server is
Authoritative over its private namespace, it has no way of knowing about the
public DNS that is Authoritative over the public namespace. All machines
under the Private namespace must use the internal DNS to find resources
within their local domain. So in order for users to find the website that is
in the public domain it will have to resolve the name
www.example.com. In
order for the internal DNS to resolve the name you must add an "A" record
named www with the public address.
Name Type Data
www A <publicipaddress>
You can also delegate the name on the private domain to the public DNS
servers that are authoritative over the public domain. So you create a
delegation using the delegation wizard, name it www the give it the names
and addresses of the public DNS servers.
This link might help you.
Domain Name System (DNS) Center
http://www.microsoft.com/Windows2000/technologies/communications/dns/default.asp