Page "Load balancing (computing)" Paragraph 20

This way, when a server is down, its DNS will not respond and the web service does not receive any traffic.

If the line to one server is congested, the unreliability of DNS ensures less HTTP traffic reaches that server.

Furthermore, the quickest DNS response to the resolver is nearly always the one from the network's closest server, ensuring geo-sensitive load-balancing.

A short TTL on the A-record helps to ensure traffic is quickly diverted when a server goes down.

Consideration must be given the possibility that this technique may cause individual clients to switch between individual servers in mid-session.