This article was previously published under Q168321
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You may have a computer with two or more network interface cards (NICs), orone NIC with more than one IP address, and need to add a record for theadditional IP address(es) to your Domain Name Service (DNS) server. Thisarticle explains how to add this entry.
An "A" record needs to be created for each IP address that the host uses.
For example, you have a server whose DNS host name is <myserver> and DNSdomain name is <mydomain.com>. This server has 2 IP addresses assigned toit: IPAddress1 and IPAddress2 (replace IPAddress1 and IPAddress2 withserver's IP addresses).
To add these IP addresses, create 2 A records in the <mydomain.com> zone:
Myserver A <IPAddress1> Myserver A <IPAddress2>
NOTE: The Microsoft DNS Server supports round robin, which is a techniqueused as a form of load balancing between servers (to get more informationabout this feature, refer to RFC 1794). This feature will make DNS sendboth IP addresses when a query is received for myserver.mydomain.com. Theclient (or Resolver) will always use the first one. The next time DNSreceives a query for this name the order of the list of IP addresses ischanged in a round robin fashion (the address that was first in theprevious list will be last in the new list). Round Robin of Cname records is not supported because there should be only one canonical name for any one alias.
If, for some reason, you need the Resolver to get the same IP address everytime, create two more "A" records assigning a unique name to each address.For example, you can create:
Altname1 A <IPAddress1> Altname2 A <IPAddress2>
Using this method, a Resolver will always obtain IPAddress1 when sending aquery for Altname1 and will always obtain IPAddress2 when sending a queryfor Altname2.
NOTE: A "CNAME" record is not used, since DNS will look up the IP addressof <Myserver>, returning the 2 IP addresses.
See RFC 2181 for more information.
DNS multi-homed multiple IP Addresses Multihomed multi homed