Routing policies (simple, weighted, latency) in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does a simple routing policy behave in AWS Route 53?

You have a Route 53 record with a simple routing policy pointing to a single IP address. What happens when a user queries this DNS record?

A The DNS query returns multiple IP addresses in a round-robin fashion.

B The DNS query returns the single IP address every time.

C The DNS query returns IP addresses based on the user's geographic location.

D The DNS query returns IP addresses weighted by traffic percentage.

💡 Hint

Simple routing returns one fixed answer.

Simple routing returns the single value configured for the DNS record every time a query is made.

❓ Architecture

intermediate

Weighted routing policy distribution

You configure two Route 53 records with weighted routing: one with weight 70 and the other with weight 30. What is the expected behavior when users query this DNS record?

A 70% of queries return the first record's IP, 30% return the second record's IP.

B All queries return the IP of the record with the higher weight.

C Queries are routed based on the lowest latency between user and record.

D Queries are routed randomly without considering weights.

💡 Hint

Weighted routing splits traffic based on weights.

Weighted routing distributes DNS responses according to the weights assigned to each record, roughly matching the percentage of traffic.

❓ service_behavior

advanced

Latency routing policy behavior

You have two AWS regions with Route 53 latency routing records. A user in Europe queries the DNS. Which IP address will Route 53 return?

A The IP address of the region with the lowest latency to the user in Europe.

B The IP address of the region with the highest weight assigned.

C The IP address of the region closest geographically to the user, ignoring latency.

D The IP address of the region with the most health checks passing.

💡 Hint

Latency routing chooses the fastest region for the user.

Latency routing returns the IP address of the AWS region that provides the lowest network latency to the user.

❓ security

advanced

Impact of health checks on weighted routing

In a weighted routing setup with two records, one record's health check fails. What happens to DNS queries?

A DNS queries fail with an error until the unhealthy record recovers.

B DNS queries continue to be routed based on weights, ignoring health checks.

C DNS queries are routed randomly between both records.

D All DNS queries are routed to the healthy record regardless of weights.

💡 Hint

Health checks remove unhealthy endpoints from routing.

When a health check fails, Route 53 stops routing traffic to that record, sending all queries to healthy records.

🧠 Conceptual

expert

Combining latency and weighted routing policies

You want to route traffic to two AWS regions using latency routing but also want to control traffic distribution with weights. Which approach is valid?

A Create weighted routing records for each region, then create latency records as children of weighted records.

B Use latency routing for regions and assign weights directly to latency records; Route 53 supports this combination.

C Route 53 does not support combining latency and weighted routing policies on the same DNS name.

D Create latency routing records for each region, then create weighted records as children of latency records.

💡 Hint

Route 53 routing policies are mutually exclusive per record name.

Route 53 does not allow combining latency and weighted routing policies on the same DNS record name. You must choose one routing policy per record name.

Practice

1. What does a simple routing policy do in AWS Route 53?

easy

A. Sends all traffic to a single resource

B. Splits traffic based on weights

C. Routes traffic based on lowest latency

D. Routes traffic randomly among resources

Solution

1. Step 1: Understand simple routing purpose

   Simple routing sends all user requests to one resource without splitting or conditions.

2. Step 2: Compare with other routing types

   Weighted routing splits traffic, latency routing chooses fastest server, so they differ from simple routing.

3. Final Answer:

   Sends all traffic to a single resource -> Option A

4. Quick Check:

   Simple routing = single destination [OK]

Hint: Simple routing means one destination for all traffic [OK]

Common Mistakes:

• Confusing simple routing with weighted routing
• Thinking simple routing balances traffic
• Assuming simple routing uses latency

2. Which of the following is the correct way to configure a weighted routing policy in AWS Route 53?

easy

A. Assign weights to each record to split traffic

B. Set a single IP address for all traffic

C. Use latency measurements to route traffic

D. Randomly assign traffic without weights

Solution

1. Step 1: Identify weighted routing configuration

   Weighted routing requires assigning numeric weights to DNS records to control traffic distribution.

2. Step 2: Eliminate incorrect options

   Single IP is simple routing, latency routing uses latency, random without weights is invalid.

3. Final Answer:

   Assign weights to each record to split traffic -> Option A

4. Quick Check:

   Weighted routing = assign weights [OK]

Hint: Weighted routing needs numeric weights per record [OK]

Common Mistakes:

• Confusing weighted with simple routing
• Using latency instead of weights
• Not assigning any weight values

3. Given two servers in different regions with latency routing enabled, which server will Route 53 direct a user to?

medium

A. The server with the highest weight

B. The server with the lowest latency from the user

C. The server with the most traffic

D. The server randomly chosen

Solution

1. Step 1: Understand latency routing behavior

   Latency routing sends users to the server with the lowest network delay from their location.

2. Step 2: Exclude other options

   Weight is for weighted routing, traffic volume is not a factor, random choice is not latency routing.

3. Final Answer:

   The server with the lowest latency from the user -> Option B

4. Quick Check:

   Latency routing = fastest server [OK]

Hint: Latency routing picks fastest server by user location [OK]

Common Mistakes:

• Mixing weighted and latency routing concepts
• Assuming traffic volume affects routing
• Thinking routing is random

4. You configured weighted routing but all traffic still goes to one server. What is the most likely cause?

medium

A. DNS records have different names

B. Latency routing is enabled instead of weighted

C. Simple routing policy is selected by mistake

D. Weights are set to zero for other servers

Solution

1. Step 1: Check weight values in weighted routing

   If weights for other servers are zero, all traffic goes to the server with non-zero weight.

2. Step 2: Rule out other causes

   Latency routing or simple routing would behave differently; different record names do not affect routing weights.

3. Final Answer:

   Weights are set to zero for other servers -> Option D

4. Quick Check:

   Zero weights = no traffic [OK]

Hint: Check weights are not zero for all servers [OK]

Common Mistakes:

• Confusing routing policy type
• Ignoring zero weights effect
• Assuming DNS names affect weighted routing

5. You want to route 70% of traffic to a primary server and 30% to a backup server, but also ensure users connect to the lowest latency server within those groups. Which routing policy setup should you use?

hard

A. Use latency routing only with weights assigned

B. Use simple routing with latency routing

C. Use weighted routing with latency routing inside each weight group

D. Use weighted routing only without latency

Solution

1. Step 1: Understand combined routing needs

   You want to split traffic by weight, then route users to lowest latency server within each group.

2. Step 2: Identify correct routing policy combination

   Weighted routing controls traffic percentage, latency routing directs users to fastest server inside each weighted group.

3. Step 3: Eliminate incorrect options

   Simple routing cannot split traffic; latency routing alone can't assign weights; weighted routing alone ignores latency.

4. Final Answer:

   Use weighted routing with latency routing inside each weight group -> Option C

5. Quick Check:

   Combine weighted + latency for split and speed [OK]

Hint: Combine weighted and latency routing for split and speed [OK]

Common Mistakes:

• Trying to use simple routing for traffic split
• Ignoring latency inside weighted groups
• Assuming latency routing can split traffic by weight