Global networking: SAA-C03 study notes and practice questions
What to know about Global networking for the SAA-C03 exam, from the Design High-Performing Architectures domain (24% of the exam guide), then 1 free question to test it. Part of the SAA-C03 study guide.
Global networking questions describe users spread around the world and an application in one or more Regions. Two services do most of the work, and they solve different problems.
CloudFront vs Global Accelerator
Amazon CloudFront
AWS Global Accelerator
What it does
Caches and serves HTTP(S) content at edge locations
Routes TCP and UDP traffic over the AWS network to the nearest healthy endpoint
Protocols
HTTP, HTTPS, WebSocket
TCP, UDP (any application)
Caching
Yes
No
Addresses
DNS name with changing IPs
Two static anycast IPv4 addresses (dual-stack accelerators add IPv6)
Failover
Origin failover between origin groups
Health checks move traffic to another endpoint or Region in seconds, with no DNS caching delay
Typical use
Websites, APIs, video, downloads
Gaming, VoIP, IoT, apps that need fixed IPs for allow lists, fast regional failover
Other pieces
Route 53 latency routing sends users to the nearest Region by DNS; it’s cheaper than Global Accelerator but depends on DNS caching for failover.
AWS Direct Connect is a private, dedicated link from your data center to AWS, with consistent performance; Site-to-Site VPN is quicker to set up over the internet.
Transit Gateway inter-Region peering connects VPC networks across Regions.
Elastic Load Balancing works within a Region: ALB for HTTP routing (paths, hosts, headers), NLB for TCP/UDP with very high performance and static IPs per zone.
AWS Local Zones and Wavelength put compute closer to specific cities or 5G networks for single-digit millisecond latency.
How to choose
“Clients have our IP addresses hard-coded” or “partners allow-list two IPs”: Global Accelerator.
“Multiplayer game over UDP for players worldwide”: Global Accelerator.
“Static site and images load slowly for overseas users”: CloudFront.
“Fail over between Regions in seconds without waiting for DNS TTLs”: Global Accelerator.
Common traps
CloudFront for UDP traffic. It doesn’t carry UDP.
Global Accelerator to reduce origin load. It doesn’t cache.
DNS-based failover when clients can’t change address. Use static IPs.
A games studio runs a real-time multiplayer game that uses UDP.
Game servers run behind Network Load Balancers in eu-west-2 and us-east-1. The game client ships with a fixed list of server IP addresses that cannot be changed after release.
Players around the world need low, consistent latency, and if one Region fails, players must be able to reconnect to the other Region within a minute without any change to the client.
Which solution meets these requirements?
Choose one answer.
AA. Assign Elastic IP addresses to each Network Load Balancer, and use Amazon Route 53 latency-based records with health checks to return the nearest healthy Region.
BB. Create an AWS Global Accelerator standard accelerator with a UDP listener, and use an Application Load Balancer in each Region as the endpoint.
CC. Create an Amazon CloudFront distribution with an origin group that contains both Regions' Network Load Balancers, so requests fail over between the origins.
DD. Create an AWS Global Accelerator standard accelerator with a UDP listener and an endpoint group in each Region that contains that Region's Network Load Balancer.
Show the answer and explanation
Answer: D
A. Wrong: Network Load Balancers support UDP and can have static Elastic IP addresses, and Route 53 can steer DNS lookups by latency and health. But the client connects to fixed IP addresses rather than resolving DNS, so when a Region fails it keeps trying that Region's addresses. Global Accelerator keeps the same addresses during failover. Learn more: Latency-based routing (opens in a new tab)
B. Wrong: Global Accelerator gives the static addresses and fast failover, but Application Load Balancers only have HTTP and HTTPS listeners, so they cannot receive the game's UDP traffic. The existing Network Load Balancers, which support UDP, should stay as the endpoints. Learn more: Listeners for your Application Load Balancers (opens in a new tab)
D. Right: Correct. The accelerator's two static anycast IP addresses can be built into the client and never change. Traffic enters the AWS network at the nearest edge location for lower, steadier latency, and Global Accelerator moves traffic to the healthy Region's endpoint group without any DNS or client change. Learn more: What is AWS Global Accelerator? (opens in a new tab)
Explanation
The hard-coded client rules out anything that changes the address a player connects to, including DNS-based failover. Global Accelerator provides two static anycast IPv4 addresses that stay with the accelerator, carries TCP and UDP from the nearest edge location over the AWS network, and reacts to endpoint health by routing to the other Region. Its endpoints must handle UDP, so the Network Load Balancers are the right endpoints; Application Load Balancers and CloudFront only handle HTTP-based traffic.
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