Working with Global Availability Load Balancing
3-DNS® Administrator Guide 9 - 1
Overview of the Global Availability load balancing mode
You can use the Global Availability mode in one of two ways: either to load
balance among wide IP pools, or to load balance within a wide IP pool.
When you use the Global Availability mode to load balance among pools,
the 3-DNS Controller continually sends requests to the first pool in the wide
IP. When all the virtual servers in the pool become unavailable, the pool is
marked unavailable and the 3-DNS Controller starts sending requests to the
next pool listed in the wide IP. When the first pool is available again, the
3-DNS Controller stops sending requests to the second pool, and starts
sending them to the first pool again. If you have an origin site and an
overflow network, such as a CDN, you can use Global Availability to load
balance between the two networks.
When you use the Global Availability mode to load balance virtual servers
within a pool, the load balancing works in much the same way. The 3-DNS
Controller repeatedly selects the first available virtual server in the wide IP
pool to respond to requests. If that virtual server becomes unavailable,
subsequent connections go to the next available virtual server listed in the
pool. When the first listed virtual server becomes available again, the
3-DNS Controller distributes requests to it again.