Exams / SAP-C03 / Study guide / Global traffic routing (Route 53 policies, Global Accelerator)
Global traffic routing (Route 53 policies, Global Accelerator): SAP-C03 study notes and practice questions
What to know about Global traffic routing (Route 53 policies, Global Accelerator) for the SAP-C03 exam, from the Architecture Design and Implementation Built for the Cloud domain (25% of the exam guide), then 1 free question to test it. Part of the SAP-C03 study guide.
SAP-C03 asks how to route users across Regions for latency, compliance, gradual migration or failover, and how fast each approach reacts when a Region degrades.
Route 53 routing policies
Policy
Routes by
Typical use
Simple
One record, no health checks
Single resource
Weighted
Percentages
Gradual migration, blue/green between Regions
Latency
Lowest measured latency Region
Active-active global apps
Failover
Primary, then secondary when unhealthy
Active-passive DR
Geolocation
User’s continent, country or US state
Content rules, data residency, licensing (add a default record)
Geoproximity
Distance with an adjustable bias
Shifting load between Regions by geography
IP-based
Client CIDR blocks you define
Routing by ISP or known networks
Multivalue answer
Up to 8 healthy records
Simple client-side load spreading
Health checks monitor endpoints, other health checks (calculated) or CloudWatch alarms (for private resources). Alias records to ELB, CloudFront and others can evaluate target health.
DNS failover depends on TTLs and client caching, so it takes longer than a network-level switch.
For controlled, reliable Region failover, Application Recovery Controller routing controls flip Route 53 health checks through a highly available data plane.
AWS Global Accelerator
Two static anycast IP addresses that enter the AWS network at the nearest edge location, then ride the AWS backbone to the best healthy endpoint.
Supports TCP and UDP; endpoints are ALBs, NLBs, EC2 instances and Elastic IPs in one or more Regions.
Fast failover without DNS caching delays; traffic dials shift a percentage per Region and endpoint weights within one.
Client affinity keeps users on the same endpoint; custom routing accelerators map users to specific EC2 instances (such as game servers).
Global Accelerator or CloudFront
CloudFront caches HTTP content at the edge. Global Accelerator doesn’t cache; it improves performance and availability for non-HTTP protocols, dynamic TCP traffic and cases needing fixed IPs.
How to choose
Scenario wording
Choose
“Users must be served from their own country’s Region”
Geolocation routing
“Send each user to the fastest Region”
Latency routing (or Global Accelerator)
“Move 10% of traffic to the new Region”
Weighted routing or traffic dials
“Partners allowlist two fixed IPs; multi-Region failover in seconds”
Global Accelerator
“UDP game traffic worldwide”
Global Accelerator
“Active-passive with a standby Region”
Failover routing with health checks
Common traps
Geolocation without a default record, so unmatched users get no answer.
Latency routing for compliance; it ignores borders.
Long TTLs that delay failover.
CloudFront for UDP or non-HTTP traffic.
Health checks on private endpoints without a CloudWatch alarm-based check.
A logistics firm's handheld scanners talk to a custom TCP service on port 8443 that runs in two AWS Regions. Port 8443 is not HTTP, so the service sits behind Network Load Balancers. The scanner firmware resolves the service name once at startup and caches the answer until the device restarts.
The firm's carrier partners must allowlist a fixed set of IP addresses, so the addresses must not change when traffic moves between Regions. If one Region becomes unhealthy, scanner traffic must move to the other Region within about a minute, without the partners changing their firewalls.
Which solution meets these requirements?
Choose one answer.
AA. Create an AWS Global Accelerator accelerator with a TCP listener on port 8443, add the Network Load Balancer in each Region as an endpoint, and give the partners the accelerator's static IP addresses.
BB. Create Amazon Route 53 failover records that point to each Region's Network Load Balancer, assign Elastic IP addresses to both load balancers, and give the partners all of those addresses to allowlist.
CC. Create an Amazon CloudFront distribution with an origin group that fails over between the two Regions' Network Load Balancers, and have the partners allowlist CloudFront's published IP ranges.
DD. Place an Application Load Balancer with AWS WAF in each Region, and use Route 53 weighted records to split scanner traffic between them.
Show the answer and explanation
Answer: A
A. Right: Correct. Global Accelerator gives two static anycast IP addresses that stay the same, and it routes to the healthier Region when an endpoint fails. It works for TCP traffic on any port.
B. Wrong: The partners could allowlist both Regions' fixed addresses, but failover depends on the scanners resolving DNS again. Because the scanners cache the answer until they restart, traffic would not move to the other Region within a minute.
C. Wrong: CloudFront serves HTTP and HTTPS traffic, not custom TCP on port 8443. The published IP ranges are also shared by many customers, which makes an allowlist too broad.
D. Wrong: An Application Load Balancer handles HTTP and HTTPS, so it cannot carry the custom TCP service. Weighted records also do not give the partners fixed addresses.
Explanation
Global Accelerator provides static IP addresses for TCP traffic and health-based failover between Regions without any DNS change, so cached answers on the scanners do not matter. DNS failover depends on new lookups, CloudFront does not carry custom TCP, and an Application Load Balancer cannot carry the non-HTTP protocol.
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