Health checks with Route 53 in AWS - Step-by-Step Execution

Process Flow - Health checks with Route 53

Create Health Check

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Route 53 Monitors Endpoint

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Health Check Status: Healthy?

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Route Traffic

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End User Gets

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Normal Response

Route 53 creates a health check to monitor an endpoint. If healthy, traffic flows normally. If unhealthy, Route 53 redirects traffic or sends alerts.

Execution Sample

AWS

Create health check for example.com
Route 53 checks endpoint every 30 seconds
If endpoint responds OK, mark healthy
If fails 3 times, mark unhealthy
Route 53 routes traffic based on health

This setup monitors a website and routes traffic only if the site is healthy.

Process Table

Step	Action	Health Check Result	Route 53 Decision	Traffic Behavior
1	Route 53 sends health check request	No response yet	Waiting	Traffic normal (initial)
2	Endpoint responds OK	Healthy	Route 53 marks healthy	Traffic routed to endpoint
3	Route 53 sends health check request	Healthy	No change	Traffic routed to endpoint
4	Endpoint does not respond	Unhealthy count 1	Still healthy (threshold not met)	Traffic routed to endpoint
5	Endpoint does not respond	Unhealthy count 2	Still healthy (threshold not met)	Traffic routed to endpoint
6	Endpoint does not respond	Unhealthy count 3	Marked unhealthy	Traffic redirected or failover triggered
7	Route 53 sends health check request	Endpoint recovers	Marked healthy	Traffic routed back to endpoint

💡 Health check marks unhealthy after 3 failures and redirects traffic accordingly

Status Tracker

Variable	Start	After Step 2	After Step 5	After Step 6	After Step 7
Health Check Status	Unknown	Healthy	Healthy (unhealthy count 2)	Unhealthy	Healthy
Unhealthy Count	0	0	2	3	0
Traffic Routing	Normal	Normal	Normal	Redirected	Normal

Key Moments - 2 Insights

Why does Route 53 wait for 3 failed checks before marking unhealthy?

Route 53 uses a threshold of 3 failures to avoid false alarms from temporary glitches, as shown in steps 4-6 where unhealthy count increases before status changes.

What happens to traffic when the health check status changes to unhealthy?

At step 6, once unhealthy count reaches 3, Route 53 marks the endpoint unhealthy and redirects traffic or triggers failover, preventing users from reaching a bad endpoint.

Visual Quiz - 3 Questions

Look at the execution table, what is the health check status at step 5?

A Unknown

B Healthy

C Unhealthy

D Degraded

💡 Hint

Check the 'Health Check Result' column at step 5 in the execution table.

At which step does Route 53 redirect traffic due to health check failure?

A Step 4

B Step 5

C Step 6

D Step 7

💡 Hint

Look at the 'Traffic Behavior' column where traffic changes from normal to redirected.

If the endpoint recovers at step 7, what happens to the unhealthy count?

A It resets to 0

B It stays at 3

C It increases to 4

D It decreases to 2

💡 Hint

Refer to the 'Unhealthy Count' variable in the variable tracker after step 7.

Concept Snapshot

Route 53 health checks monitor endpoints regularly.
If endpoint fails checks 3 times, Route 53 marks it unhealthy.
Traffic is redirected or failover triggered on unhealthy.
When endpoint recovers, health status resets and traffic returns.
This ensures users reach healthy resources only.

Full Transcript

This visual execution shows how AWS Route 53 health checks work. First, Route 53 creates a health check for an endpoint. It sends requests every 30 seconds. If the endpoint responds OK, Route 53 marks it healthy and routes traffic normally. If the endpoint fails to respond three times in a row, Route 53 marks it unhealthy and redirects traffic to a backup or triggers an alert. When the endpoint recovers, Route 53 marks it healthy again and resumes normal traffic routing. This process helps keep user traffic flowing only to healthy resources, improving reliability.

Practice

1. What is the main purpose of a health check in AWS Route 53?

easy

A. To monitor if a website or server is working properly

B. To increase the storage capacity of a server

C. To speed up the DNS resolution process

D. To encrypt data between users and servers

Solution

1. Step 1: Understand the role of health checks

   Health checks in Route 53 monitor the status of your website or server to see if it is working correctly.

2. Step 2: Identify the main purpose

   The main goal is to ensure traffic is sent only to healthy endpoints by checking their health status.

3. Final Answer:

   To monitor if a website or server is working properly -> Option A

4. Quick Check:

   Health check purpose = Monitor server health [OK]

Hint: Health checks watch if your site/server is up [OK]

Common Mistakes:

• Confusing health checks with encryption
• Thinking health checks speed up DNS
• Assuming health checks add storage

2. Which of the following is the correct way to configure a Route 53 health check to check an HTTP endpoint on port 80?

easy

A. Set Protocol to FTP and Port to 21

B. Set Protocol to HTTPS and Port to 443

C. Set Protocol to TCP and Port to 22

D. Set Protocol to HTTP and Port to 80

Solution

1. Step 1: Identify the protocol and port for HTTP

   HTTP uses protocol HTTP and port 80 by default.

2. Step 2: Match the correct configuration

   Setting Protocol to HTTP and Port to 80 correctly configures the health check for an HTTP endpoint.

3. Final Answer:

   Set Protocol to HTTP and Port to 80 -> Option D

4. Quick Check:

   HTTP = Protocol HTTP + Port 80 [OK]

Hint: HTTP always uses port 80 [OK]

Common Mistakes:

• Using HTTPS protocol for HTTP checks
• Choosing wrong ports like 22 or 21
• Confusing TCP with HTTP protocol

3. Given a Route 53 health check configured to check an HTTP endpoint every 30 seconds with a failure threshold of 3, how long will it take before Route 53 marks the endpoint as unhealthy after it stops responding?

medium

A. 30 seconds

B. 60 seconds

C. 90 seconds

D. 120 seconds

Solution

1. Step 1: Understand failure threshold and interval

   The health check runs every 30 seconds and requires 3 consecutive failures to mark unhealthy.

2. Step 2: Calculate total time to mark unhealthy

   3 failures x 30 seconds each = 90 seconds before marking unhealthy.

3. Final Answer:

   90 seconds -> Option C

4. Quick Check:

   3 failures x 30s = 90s [OK]

Hint: Multiply interval by failure threshold [OK]

Common Mistakes:

• Using interval time only without threshold
• Adding instead of multiplying
• Confusing seconds with minutes

4. You created a Route 53 health check for an HTTPS endpoint on port 443, but Route 53 always marks it unhealthy even though the site is up. What is the most likely cause?

medium

A. The health check is set to HTTP instead of HTTPS

B. The failure threshold is set too high

C. The endpoint is using port 80 instead of 443

D. The health check is configured with TCP protocol

Solution

1. Step 1: Check protocol mismatch

   If the health check is set to HTTP but the endpoint requires HTTPS, the check will fail.

2. Step 2: Confirm correct protocol and port

   HTTPS requires protocol HTTPS and port 443; using HTTP protocol causes failure.

3. Final Answer:

   The health check is set to HTTP instead of HTTPS -> Option A

4. Quick Check:

   Protocol mismatch causes failure [OK]

Hint: Match protocol exactly with endpoint [OK]

Common Mistakes:

• Ignoring protocol and port mismatch
• Assuming failure threshold causes failure
• Confusing TCP with HTTPS protocol

5. You want Route 53 to route traffic only to healthy web servers in multiple regions. You have health checks set up for each server. Which routing policy should you use to ensure traffic goes only to healthy servers and balances load across them?

hard

A. Simple routing policy

B. Weighted routing policy with health checks enabled

C. Latency routing policy without health checks

D. Failover routing policy

Solution

1. Step 1: Understand routing policies

   Simple routing sends traffic to one resource; failover sends to primary then backup; weighted distributes traffic by weights; latency routes to lowest latency.

2. Step 2: Choose policy that balances load and respects health

   Weighted routing with health checks enabled sends traffic only to healthy servers and balances load based on weights.

3. Final Answer:

   Weighted routing policy with health checks enabled -> Option B

4. Quick Check:

   Weighted + health checks = balanced healthy routing [OK]

Hint: Use weighted routing with health checks for balanced healthy traffic [OK]

Common Mistakes:

• Using simple routing which ignores health checks
• Failover only switches on failure, no load balance
• Latency routing without health checks risks unhealthy targets