This section covers the user request flow for the GSLB application.
- FQDN Address Resolution
Figure 1 shows a client sending an HTTPS request to download the home page of application A. Its FQDN (A.acme.com) must be mapped to an IP address that is not yet known to the client. A hierarchical tree of DNS resolvers eventually identifies the corporate DNS for acme.com.
The corporate DNS forwards the request to one of the three GSLB DNS instances since domain A.acme.com has been delegated to the NSX Advanced Load Balancer's global DNS (in this case to DNS-2).
DNS-2 has four candidates for the optimal virtual sevice choice: VS-A1, VS-A2, VS-A3, and VS-A4. It selects VS-A3 based on the load balancing algorithm, health, client location, and other factors. DNS-2 responds to the DNS query with the VIP of VS-A3, which eventually reaches the original client.
- Application Traffic Flows to Optimal Virtual Service
Figure 2 shows the client using the VIP of VS-A3 to send its HTTP request.
- Local Load Balancing
Figure 3 shows one of the SEs in the SE group receiving the request directed to the VIP of VS-A3. It then load-balances it to one of VS-A3’s 3 servers. VS-A3 responds directly to the client.