Route 53 with ELB integration in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Amazon Route 53?

Amazon Route 53 is a cloud service that helps direct internet traffic to your websites by translating domain names into IP addresses.

beginner

What does ELB stand for and what is its role?

ELB stands for Elastic Load Balancer. It automatically distributes incoming traffic across multiple servers to keep your application reliable and fast.

intermediate

How does Route 53 integrate with ELB?

Route 53 can point your domain name to an ELB by creating an alias record. This lets Route 53 send traffic directly to the load balancer without needing an IP address.

intermediate

Why use an alias record in Route 53 for ELB instead of a CNAME?

Alias records are free and can point to AWS resources like ELB directly at the root domain, unlike CNAMEs which can't be used at the root and may incur extra costs.

intermediate

What happens if the ELB changes its IP addresses?

Because Route 53 uses alias records pointing to the ELB's DNS name, it automatically tracks IP changes. This means your domain always routes correctly without manual updates.

What type of Route 53 record should you use to point your domain to an ELB?

A Alias record

B CNAME record

C TXT record

D MX record

Alias records are designed to point to AWS resources like ELB and work at the root domain level.

Why is using an alias record with ELB beneficial?

A It costs extra money

B It requires manual IP updates

C It automatically updates if ELB IPs change

D It only works with IPv6

Alias records track ELB DNS names, so IP changes are handled automatically.

Which AWS service distributes traffic across multiple servers?

A CloudWatch

B S3

C Route 53

D Elastic Load Balancer

Elastic Load Balancer distributes incoming traffic to multiple servers.

Can you use a CNAME record at the root domain to point to an ELB?

A Yes, always

B No, CNAMEs are not allowed at root domains

C Only for IPv6

D Only with alias records

DNS rules prevent CNAME records at the root domain; alias records solve this.

What does Route 53 do when it receives a request for your domain?

A Translates domain to IP and sends traffic to ELB

B Stores website files

C Monitors server health

D Creates new servers

Route 53 translates domain names to IP addresses or AWS resources like ELB.

Explain how Route 53 and ELB work together to route internet traffic to your application.

Think about how your website address connects to your servers through AWS.

Describe the benefits of using alias records in Route 53 when integrating with ELB.

Consider why alias records are preferred over CNAME for ELB.

Practice

1. What is the main benefit of using a Route 53 alias record with an Elastic Load Balancer (ELB)?

easy

A. It allows you to point your domain directly to the ELB without using an IP address.

B. It automatically creates a backup server for your website.

C. It encrypts all traffic between users and the ELB.

D. It reduces the cost of running the ELB.

Solution

1. Step 1: Understand Route 53 alias records

   Alias records let you point your domain name to AWS resources like ELB without needing an IP address.

2. Step 2: Recognize ELB integration benefit

   This simplifies DNS management and handles ELB IP changes automatically.

3. Final Answer:

   It allows you to point your domain directly to the ELB without using an IP address. -> Option A

4. Quick Check:

   Alias record points domain to ELB without IP [OK]

Hint: Alias records link domains to ELB without IPs [OK]

Common Mistakes:

• Thinking alias records create backups
• Confusing alias with encryption
• Assuming alias reduces ELB cost

2. Which of the following is the correct way to create a Route 53 alias record pointing to an ELB in the AWS console?

easy

A. Create a CNAME record pointing to the ELB's IP address.

B. Create an A record and enter the ELB's IP address manually.

C. Create an A record and select 'Alias' with the ELB as the target.

D. Create a TXT record with the ELB's DNS name.

Solution

1. Step 1: Know Route 53 record types for ELB

   ELB does not have fixed IPs, so you cannot use IP addresses directly.

2. Step 2: Use alias A record

   Route 53 allows creating an A record with alias enabled, selecting the ELB DNS name as target.

3. Final Answer:

   Create an A record and select 'Alias' with the ELB as the target. -> Option C

4. Quick Check:

   Alias A record points to ELB DNS [OK]

Hint: Use alias A record, not IP or CNAME for ELB [OK]

Common Mistakes:

• Using IP address for ELB
• Choosing CNAME instead of alias A record
• Using TXT record incorrectly

3. Given a Route 53 setup with an alias record pointing to an ELB, what happens if the ELB becomes unhealthy and fails its health checks?

medium

A. Route 53 continues sending traffic to the ELB regardless of health status.

B. Route 53 automatically stops sending traffic to the ELB until it is healthy again.

C. Route 53 deletes the alias record automatically.

D. Route 53 redirects traffic to a backup IP address.

Solution

1. Step 1: Understand Route 53 health checks with ELB

   Route 53 alias records pointing to ELB do not automatically stop sending traffic if the ELB is unhealthy because ELB manages its own health and traffic routing internally.

2. Step 2: Behavior on ELB failure

   Route 53 continues to resolve the alias record to the ELB DNS name regardless of ELB health status; ELB itself stops routing traffic to unhealthy targets.

3. Final Answer:

   Route 53 continues sending traffic to the ELB regardless of health status. -> Option A

4. Quick Check:

   Route 53 alias records do not perform health-based routing for ELB [OK]

Hint: ELB manages health; Route 53 alias does not stop traffic [OK]

Common Mistakes:

• Thinking Route 53 stops traffic to unhealthy ELB
• Assuming Route 53 deletes records on failure
• Believing Route 53 redirects to IP automatically

4. You created a Route 53 alias record to an ELB, but your website is not reachable. Which of the following is the most likely cause?

medium

A. The domain name is missing a trailing dot in the alias record.

B. The alias record is set as a CNAME instead of an A record with alias enabled.

C. The alias record points to the ELB DNS name, but the ELB is in a different AWS region than the hosted zone.

D. The ELB does not have any registered healthy targets.

Solution

1. Step 1: Check ELB target health

   If ELB has no healthy targets, it cannot serve traffic, causing website unreachable.

2. Step 2: Verify alias record and region

   Alias records can point across regions; CNAME is invalid for alias; trailing dot is not required for alias.

3. Final Answer:

   The ELB does not have any registered healthy targets. -> Option D

4. Quick Check:

   Healthy targets needed for ELB to serve traffic [OK]

Hint: Check ELB target health if site unreachable [OK]

Common Mistakes:

• Confusing alias record type
• Assuming region mismatch breaks alias
• Thinking trailing dot is required

5. You want to configure Route 53 to route traffic to two ELBs in different regions for high availability. Which setup ensures traffic is sent only to healthy ELBs and balances load between them?

hard

A. Create two CNAME records with the same domain name pointing to each ELB's DNS name.

B. Create two alias A records with the same domain name, each pointing to one ELB, and enable health checks on both records.

C. Create a single alias A record pointing to the ELB in the primary region and manually switch to the other ELB if failure occurs.

D. Create two alias A records with different domain names and use a third DNS service to balance traffic.

Solution

1. Step 1: Use alias A records with health checks

   Route 53 supports multiple alias records with health checks to route traffic only to healthy ELBs.

2. Step 2: Load balancing across regions

   By creating two alias records with health checks, Route 53 can balance traffic and failover automatically.

3. Final Answer:

   Create two alias A records with the same domain name, each pointing to one ELB, and enable health checks on both records. -> Option B

4. Quick Check:

   Multiple alias records + health checks = HA and load balancing [OK]

Hint: Use multiple alias records with health checks for HA [OK]

Common Mistakes:

• Using CNAME for ELB alias
• Manual failover instead of health checks
• Using different domain names for ELBs