QuestionQ61

Network Design

A company has deployed an application where the application front end communicates with backend instances through a Network Load Balancer (NLB) in the same VPC. The application is highly available in two Availability Zones. The company needs to minimize the traffic that crosses Availability Zones. Traffic from the application front end must remain in the same Availability Zone unless no healthy target exists in that Availability Zone behind the NLB. If no healthy target exists in the same Availability Zone, traffic must be routed to the other Availability Zone.

Which solution meets these requirements?

  • A Create a private hosted zone with weighted routing for each Availability Zone. Point the primary record to the local Availability Zone NLB DNS record. Point the secondary record to the Regional NLB DNS record. Configure the front end of the application to perform DNS lookups on the local private hosted zone records.
  • B Turn off cross-zone load balancing on the NLConfigure the front end of the application to perform DNS lookups on the local Availability Zone NLB DNS record.
  • C Create a private hosted zone. Create a failover record for each Availability Zone. For each failover record, point the primary record to the local Availability Zone NLB DNS record and point the secondary record to the Regional NLB DNS record. Configure the front end of the application to perform DNS lookups on the local private hosted zone records.
  • D Enable sticky sessions (session affinity) so that the NLB can bind a user’s session to targets in the same Availability Zone.
Explanation

Disabling NLB cross-zone load balancing confines each load balancer node to healthy targets in its own Availability Zone. Resolving the local Availability Zone NLB DNS record keeps front-end traffic local during normal operation. When that zone has no healthy targets, the NLB removes the corresponding zonal IP address from DNS, so new connections can be directed to a healthy Availability Zone.

Learn more

Community Discussion

No comments yet. Be the first to start the discussion!