Route 53 with ELB integration in AWS - Step-by-Step Execution

Process Flow - Route 53 with ELB integration

User DNS Request

↓

Route 53 Receives Request

↓

Route 53 Checks Record Type

↓

Is it Alias to ELB?

No→Return Other Record

Yes↓

Route 53 Resolves ELB DNS Name

↓

Return ELB DNS Name to User

↓

User Connects to ELB

↓

ELB Forwards Traffic to Targets

When a user requests a domain, Route 53 checks if the record is an alias to an ELB. If yes, it returns the ELB's DNS name, directing traffic to the load balancer.

Execution Sample

AWS

Create Route 53 record:
Type: A (Alias)
Alias Target: ELB DNS name

User queries domain
Route 53 returns ELB DNS name
User connects to ELB

This setup directs user traffic from a domain name to an ELB using Route 53 alias records.

Process Table

Step	Action	Input	Decision/Result	Output
1	User sends DNS query	example.com	Route 53 receives query	Query received
2	Route 53 checks record type	example.com record	Record is Alias to ELB	Proceed to resolve ELB
3	Route 53 resolves ELB DNS	ELB DNS name	ELB DNS resolved	ELB DNS name
4	Route 53 returns ELB DNS name	ELB DNS name	DNS name sent to user	User receives ELB DNS name
5	User connects to ELB	ELB DNS name	Connection established	Traffic forwarded to ELB targets
6	ELB forwards traffic	User request	Targets respond	User gets response

💡 Process ends after ELB forwards traffic to targets and user receives response.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
DNS Query	None	example.com	example.com	example.com	example.com
Record Type	Unknown	Alias to ELB	Alias to ELB	Alias to ELB	Alias to ELB
ELB DNS	None	None	elb-123456.us-east-1.elb.amazonaws.com	elb-123456.us-east-1.elb.amazonaws.com	elb-123456.us-east-1.elb.amazonaws.com
ELB IPs	None	None	None	None	None
User Connection	None	None	None	None	Connected to ELB

Key Moments - 3 Insights

Why does Route 53 return IP addresses instead of the ELB DNS name?

Route 53 does not return IP addresses for alias records to ELB; it returns the ELB DNS name. The user then resolves the ELB DNS name to IPs. This is shown in step 4 of the execution_table.

What happens if the Route 53 record is not an alias to ELB?

Route 53 returns the record as is (like a standard A or CNAME record), shown by the 'No' branch in the concept_flow after checking record type.

How does the user traffic reach the actual servers behind the ELB?

After the user connects to the ELB DNS name, the ELB forwards traffic to its registered targets, completing the flow in step 6 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the output at step 3?

A Route 53 receives the DNS query

B ELB DNS name

C User connects to ELB

D Traffic forwarded to ELB targets

💡 Hint

Check the 'Output' column for step 3 in the execution_table.

At which step does the user receive the ELB DNS name?

A Step 4

B Step 2

C Step 5

D Step 6

💡 Hint

Look at the 'Output' column in the execution_table for when the ELB DNS name is sent to the user.

If the Route 53 record was not an alias to ELB, what would change in the execution flow?

A Route 53 would resolve ELB DNS anyway

B User would connect directly to ELB IPs

C Route 53 would return the record as is without resolving ELB

D ELB would forward traffic to Route 53

💡 Hint

Refer to the concept_flow where the decision checks if record is alias to ELB.

Concept Snapshot

Route 53 with ELB integration:
- Create an Alias A record in Route 53 pointing to ELB DNS
- Route 53 returns ELB DNS name to user DNS queries
- User traffic goes to ELB
- ELB forwards traffic to registered targets
- Alias records simplify DNS management for ELB

Full Transcript

When a user requests a domain name managed by Route 53, Route 53 checks the record type. If the record is an alias to an Elastic Load Balancer (ELB), Route 53 returns the ELB's DNS name. The user then resolves the ELB DNS name to IP addresses and connects to the ELB. The ELB then forwards the traffic to its registered backend targets. If the record is not an alias to ELB, Route 53 returns the record as is. This integration allows seamless routing of user traffic from a friendly domain name to the ELB, which balances load across servers.

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