DNS Configuration and Management Manual (G06.27+, H06.05+, J06.03+)

HP DNS Configuration and Management Manual—529432-003
4-1
4 Scaling DNS
You can scale DNS in two ways:
•
by separating traffic over physical networks
•
by using the DNS round-robin address rotation feature.
Physical Network Separation
Network scalability refers to distributing incoming requests across multiple network
interfaces. You can achieve network scalability by having multiple network interfaces
on multiple hosts/servers or by having a multi-homed host (a system that has multiple
network interfaces).
In a multi-homed system where you have multiple interfaces on multiple subnets and
where you want the system to appear to be one name while also distributing the
network traffic, you can configure DNS so that a different IP address is returned
depending on the subnet when queries for that name are received. One way to
accomplish this task is to run a copy of the DNS server on each subnet, and on each
subnet return the IP address of the interface that is on that subnet. This arrangement is
a kind of physical scaling because you are servicing clients based on the subnet on
which the client resides.
For example, assume you have four DNS name servers, one on each subnet
configured to return the IP address of the host’s interface on that subnet. All clients
requesting an IP address on that subnet are returned the IP address of the host that is
also on that subnet:
•
Clients on subnet 192.168.1.1 requesting the IP address of MyCompany.com
receive the IP address of Webserver 1.
•
Clients on subnet 192.168.2.1 requesting the IP address of MyCompany.com
receive the IP address of Webserver 2.
•
Clients on subnet 192.168.3.1 requesting the IP address of MyCompany.com
receive the IP address of Webserver 3.
•
Clients on subnet 192.168.4.1 requesting the IP address of MyCompany.com
receive the IP address of Webserver 4.