Web Caching and Replication

16.4. DNS-Based Server Selection

DNS is currently the main mechanism for request distribution over wide area (and sometimes even local area) networks. Both stand-alone Web sites and CDNs use DNS request distribution. The former often follow the basic architecture of Section 14.1.3, while the latter are likely to combine DNS request distribution with other mechanisms described in Section 15.4. The discussion in this section applies to both architectures; however, for simplicity, we only discuss server selection in the context of the basic architecture. In a CDN with server forms (see Figure 15.5), a server would correspond to a server farm, and communication between the DNS and a server would correspond to communication between the DNS and the ...