Design High-Performing Architectures
Global Delivery, Edge, and Load Balancing
CoreChoose DNS, caching, anycast acceleration, and load-balancer family from protocol and global latency requirements.
Aligned to the current SAA-C03 exam guide, verified August 16, 2026.
Why this matters
Global performance depends on where latency occurs and whether traffic is cacheable. The architect must separate DNS selection, edge caching, network-path acceleration, and regional target distribution, then choose the protocol-aware layer that solves the named bottleneck.
Must Know
- Route 53 answers DNS and applies routing policies and health evaluation; DNS changes where clients connect but does not proxy application traffic.
- CloudFront is a CDN and reverse proxy that caches eligible content at edge locations, reduces origin load, and integrates edge security. Dynamic requests can still benefit from the optimized edge-to-origin path.
- Global Accelerator provides static anycast IP addresses and carries supported TCP/UDP traffic over the AWS global network to healthy regional endpoints. It does not cache content.
- Application Load Balancer handles HTTP/HTTPS with Layer 7 host/path routing; Network Load Balancer handles high-performance Layer 4 TCP/UDP/TLS and static IP needs; Gateway Load Balancer integrates virtual network appliances.
- A load balancer distributes traffic among targets in a Region; Route 53 or Global Accelerator can steer among regional endpoints depending on DNS versus anycast/protocol needs.
- Origin placement, cache key, TTL, invalidation, and cacheability determine CloudFront effectiveness. Protect origins so clients cannot bypass intended controls when required.
- Start with protocol and cacheability, then user geography, static-IP need, health/failover scope, origin behavior, security, and cost.
Compare and Distinguish
- CloudFront vs Global Accelerator: CloudFront wins for HTTP content delivery, caching, and origin protection; Global Accelerator wins for non-cacheable TCP/UDP or applications needing static anycast IPs and global path acceleration.
- CloudFront vs Route 53: CloudFront proxies and may cache traffic; Route 53 returns DNS answers and applies routing policy.
- Route 53 vs Global Accelerator: DNS-based regional selection fits broad endpoint/routing cases; Global Accelerator fits supported endpoints needing static anycast IPs and rapid network-level health routing.
- ALB vs NLB vs Gateway Load Balancer: choose Layer 7 web routing, Layer 4 performance/static IPs, or transparent appliance insertion.
- API Gateway vs ALB: API Gateway wins for managed API authorization, throttling, and service integrations; ALB wins for HTTP distribution to application targets.
Scenario examples
- Scenario: Global users download cacheable images from S3. Think: CloudFront moves delivery to the edge and reduces origin requests.
- Scenario: A global multiplayer service uses UDP and needs static client IPs. Think: Global Accelerator, not CloudFront caching.
- Scenario: One HTTPS endpoint routes /orders and /catalog to different target groups. Think: ALB Layer 7 routing.
- Scenario: Traffic must pass transparently through a fleet of virtual firewalls. Think: Gateway Load Balancer matches the appliance insertion model.
Exam traps
- Route 53 does not cache application objects or accelerate packets after DNS resolution.
- Global Accelerator is not a CDN and does not cache responses.
- CloudFront does not make an unhealthy origin healthy.
- NLB is not chosen for host/path routing, and ALB is not the transparent appliance load balancer.
- A CDN cannot reduce origin load for content deliberately made uncacheable in the same way as cached objects.
- Static IP requirements do not automatically point to Route 53.
Key takeaways
- Choose edge service from protocol, cacheability, and client endpoint requirements.
- Use CloudFront for cacheable HTTP delivery and origin protection; Global Accelerator for supported TCP/UDP anycast acceleration.
- Use Route 53 for DNS-based routing and ELB for regional target distribution.
- Match ALB, NLB, or Gateway Load Balancer to Layer 7, Layer 4, or appliance needs.
How it works
- Route 53 evaluates routing policy and health information to return DNS answers.
- CloudFront receives viewer requests at edge locations, serves cached objects when eligible, and otherwise contacts the origin.
- Global Accelerator advertises static anycast IPs and directs traffic over the AWS network to healthy endpoints.
- ELB evaluates listeners and target health and distributes traffic within its supported scope.
When to use it
- Use CloudFront for web/static/API delivery that benefits from edge proxying or caching.
- Use Global Accelerator for supported non-cacheable TCP/UDP and static anycast requirements.
- Use Route 53 for DNS policies and failover, ALB for Layer 7, NLB for Layer 4, and Gateway Load Balancer for appliances.
Security and governance implications
- Use TLS certificates and WAF/Shield integrations at supported internet-facing layers.
- Restrict origin access so CloudFront cannot be bypassed when that is a requirement.
- Protect DNS and load-balancer configuration with least privilege and change monitoring.
- Avoid caching personalized or sensitive responses under an unsafe shared key.
Operational and diagnostic signals
- For low cache hit ratio, inspect cache keys, cookies/headers, TTL, invalidations, and object variability.
- For regional failover delay, distinguish endpoint health, DNS caching, and capacity readiness.
- For load-balancer failures, inspect listener protocol, target type, health checks, security groups, and target application health.
- For global latency, measure viewer-to-edge, edge-to-origin, and origin processing separately.
More detail
- DNS resolver caching affects how quickly Route 53 answer changes are observed by clients.
- CloudFront cache behavior depends on cache keys and policies; forwarding unnecessary variability can reduce hit ratio.
- Global services still terminate at regional endpoints whose capacity, data, and health must meet requirements.
- Edge delivery can improve latency and cost only after hard security, protocol, and consistency requirements are met.
Ready for the quiz?
- Why does cacheability separate CloudFront from Global Accelerator?
- When does Route 53 solve a problem without proxying traffic?
- Which clue favors NLB over ALB?
- When is Gateway Load Balancer decisive?
- What origin design is needed to realize CDN benefits?
Related objectives
- D2.1.K7
- D2.1.K9
- D3.4.K1
- D3.4.K3
- D3.4.S3
- D3.4.S4