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Difficulty: HardOptimizing Network Performance and Latency

A digital advertising platform operates a latency-critical ad bidding application across two VPCs in the `us-east-1` Region: `AdBiddingVPC` and `AdAnalyticsVPC`. The bidding engine running on Amazon EC2 instances in `AdBiddingVPC` needs to write real-time transactional logs to an Amazon Aurora PostgreSQL database cluster in `AdAnalyticsVPC` with a latency of less than 2 ms2\text{ ms}. Currently, the VPCs are connected using an AWS Transit Gateway. The database endpoint is hosted in a Route 53 Private Hosted Zone (PHZ) that is associated only with `AdAnalyticsVPC`. The bidding engine is currently experiencing latency spikes of over 15 ms15\text{ ms} and database connection timeouts. Network analysis shows that database DNS queries from the bidding engine resolve to a public IP address, causing the traffic to route out through a NAT Gateway in `AdBiddingVPC` and back in via the public internet. Which of the following optimization strategies should the Solutions Architect implement? (Select TWO.)

  1. Create a VPC Peering connection between AdBiddingVPC and AdAnalyticsVPC, and update the route tables to route database traffic directly through the peering connection.Answer
  2. Associate the Route 53 Private Hosted Zone containing the database DNS records with AdBiddingVPC.Answer
  3. C
    Establish an AWS Transit Gateway peering connection between AdBiddingVPC and AdAnalyticsVPC to bypass the public internet.
  4. D
    Configure a secondary NAT Gateway in a different Availability Zone within AdBiddingVPC, and route the database traffic through it to the public database endpoint.
  5. E
    Deploy an Application Load Balancer in AdAnalyticsVPC in front of the database cluster, and request AWS Support to pre-warm the load balancer to handle peak bidding volumes.

Answer

Establish a VPC Peering connection between the two VPCs to route database traffic directly, and associate the Route 53 Private Hosted Zone containing the database DNS records with the bidding VPC.
Establishing a VPC Peering connection provides a direct, high-bandwidth connection between the bidding VPC and the database VPC, satisfying the latency constraint of less than 2 ms2\text{ ms}. Associating the Route 53 Private Hosted Zone with the bidding VPC allows the bidding instances to resolve the database's endpoint to its private IP addresses, ensuring that database traffic uses the peering connection rather than routing over the public internet through a NAT Gateway.

Step-by-Step Solution

1
Identify the cause of the database latency and connection timeouts.
The Route 53 Private Hosted Zone (PHZ) is only associated with the database VPC, causing the bidding VPC's DNS queries to resolve to the database's public IP address. This forces the bidding traffic out of the NAT Gateway to the public internet.
Resolving to public IP addresses prevents the traffic from staying within the AWS private network, introducing significant round-trip time (RTT) and packet loss.
2
Establish private DNS resolution for the bidding VPC.
Associate the database's Route 53 Private Hosted Zone with the bidding VPC.
This association ensures that the bidding engine resolves the database hostname to its private IP addresses instead of public IP addresses.
3
Optimize the inter-VPC network pathway for sub-millisecond latency.
Create a VPC Peering connection between the bidding VPC and the database VPC, and update the VPC route tables.
VPC Peering provides the lowest possible latency path between VPCs in the same region, bypassing the Transit Gateway processing hop and avoiding bandwidth charges.

Key Concept

Optimizing network latency and routing path efficiency between VPCs using VPC Peering and private DNS zone associations.
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Topics

Optimizing Network Performance and Latency