Web OS 10.0 Application GuideChapter 12: Global Server Load Balancing n 291212777-A, February 2002How GSLB WorksGSLB is based on the Domain Name System (DNS) and proximity by source IP address. In theexample in Figure 12-1, a client is using a browser to view the Web site for the Foo Corporationat “www.foocorp.com.” The Foo Corporation has two Web sites: one in California, and one inDenver, each with identical content and available services. Both Web sites have an Alteon Webswitch configured for GSLB. These switches are also configured as the Authoritative NameServers for “www.foocorp.com.”Figure 12-1 DNS Resolution with Global Server Load BalancingThe DNS resolution for GSLB is described in detail in the following procedure:1. The client Web browser requests the “www.foocorp.com” IP address from the local DNS.2. Client’s DNS asks its upstream DNS, which in turn asks the next, and so on, until theaddress is resolved.Eventually, the request reaches an upstream DNS server that has the requested IP addressinformation on hand or the request reaches one of the Foo Corporation’s DNS servers.3. The Foo Corporation’s California DNS has been configured to use the local Web switchwith GSLB software as the authoritative name server for “www.foocorp.com.”InternetFoo Corp. California Foo Corp. DenverClient SiteDNSDNSWebServersWebServersDNSSwitches regularly exchange performance informationWeb SwitchWeb SwitchBest Service!4321 5DNS responselists best site'sIP address firstDNSRequest HTTPRequest
