TCP/UDP Load Balancer (Layer 4) in GCP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the protocol for the load balancer.

GCP

load_balancer_config = {
  "protocol": "[1]",
  "port": 80
}

Drag options to blanks, or click blank then click option'

ATCP

BHTTP

CHTTPS

DFTP

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing HTTP or HTTPS instead of TCP

Confusing Layer 4 with Layer 7 protocols

The TCP/UDP Load Balancer operates at Layer 4, so the protocol must be set to "TCP" or "UDP". Here, "TCP" is correct.

2fill in blank

medium

Complete the code to define the backend service type for TCP/UDP load balancing.

GCP

backend_service = {
  "type": "[1]",
  "health_check": "tcp_health_check"
}

Drag options to blanks, or click blank then click option'

AHTTPS

BHTTP

CSSL

DTCP

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTP or HTTPS as backend service type

Mixing SSL with TCP backend service type

The backend service type for a TCP/UDP load balancer should be "TCP" to match the protocol and ensure proper routing.

3fill in blank

hard

Fix the error in the health check configuration for TCP load balancer.

GCP

health_check = {
  "type": "[1]",
  "port": 443
}

Drag options to blanks, or click blank then click option'

AHTTP

BHTTPS

CTCP

DSSL

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTP or HTTPS health check for TCP load balancer

Setting incorrect port for health check

For TCP load balancers, the health check type must be "TCP" to properly check backend health at Layer 4.

4fill in blank

hard

Fill both blanks to configure the forwarding rule for a TCP load balancer.

GCP

forwarding_rule = {
  "loadBalancingScheme": "[1]",
  "portRange": "[2]"
}

Drag options to blanks, or click blank then click option'

AEXTERNAL

BINTERNAL

C80-80

D443-443

Attempts:

3 left

💡 Hint

Common Mistakes

Using INTERNAL scheme for public load balancer

Setting wrong port range that doesn't match backend service

The forwarding rule for a TCP load balancer typically uses an EXTERNAL scheme and a port range like "80-80" for HTTP traffic.

5fill in blank

hard

Fill all three blanks to define the backend instance group and balancing mode.

GCP

backend = {
  "group": "[1]",
  "balancingMode": "[2]",
  "capacityScaler": [3]
}

Drag options to blanks, or click blank then click option'

A"projects/my-project/zones/us-central1-a/instanceGroups/my-group"

B"UTILIZATION"

C1.0

D"RATE"

Attempts:

3 left

💡 Hint

Common Mistakes

Using short or incorrect instance group path

Choosing RATE balancing mode when UTILIZATION is expected

Setting capacityScaler to invalid values

The backend group must specify the full instance group path. The balancing mode "UTILIZATION" balances based on resource use, and capacityScaler 1.0 means full capacity.

Practice

1. What is the primary function of a TCP/UDP Load Balancer in GCP?

easy

A. Store and cache static website content for faster delivery

B. Analyze HTTP headers to route requests based on URL paths

C. Encrypt data packets before sending them to clients

D. Distribute incoming TCP or UDP traffic evenly across backend servers

Solution

1. Step 1: Understand Layer 4 Load Balancing

   TCP/UDP Load Balancers operate at Layer 4, handling raw TCP or UDP traffic without inspecting application data.

2. Step 2: Identify the main role

   The main role is to distribute incoming network traffic evenly across multiple backend servers to balance load and improve availability.

3. Final Answer:

   Distribute incoming TCP or UDP traffic evenly across backend servers -> Option D

4. Quick Check:

   Layer 4 Load Balancer = Traffic distribution [OK]

Hint: Layer 4 means TCP/UDP traffic distribution only [OK]

Common Mistakes:

• Confusing Layer 4 with Layer 7 load balancing
• Thinking it inspects HTTP headers
• Assuming it caches content

2. Which GCP component is essential to define where TCP/UDP Load Balancer sends traffic?

easy

A. Cloud Storage Bucket

B. Forwarding Rule

C. Cloud Pub/Sub Topic

D. Cloud SQL Instance

Solution

1. Step 1: Identify GCP components for Load Balancing

   Forwarding rules in GCP specify the IP address, port, and protocol that the load balancer listens on.

2. Step 2: Understand traffic routing

   Forwarding rules direct incoming TCP/UDP traffic to the backend service or instance group.

3. Final Answer:

   Forwarding Rule -> Option B

4. Quick Check:

   Forwarding Rule = Traffic entry point [OK]

Hint: Forwarding Rule directs traffic to backends [OK]

Common Mistakes:

• Choosing unrelated services like Cloud Storage
• Confusing Pub/Sub with load balancing
• Selecting Cloud SQL which is a database

3. Given a TCP Load Balancer with 3 backend instances, if 300 connections arrive evenly, how many connections does each instance handle?

medium

A. 100 connections

B. 300 connections

C. 150 connections

D. 50 connections

Solution

1. Step 1: Understand even distribution

   The load balancer distributes connections evenly across all backend instances.

2. Step 2: Calculate connections per instance

   300 connections divided by 3 instances equals 100 connections per instance.

3. Final Answer:

   100 connections -> Option A

4. Quick Check:

   300 ÷ 3 = 100 [OK]

Hint: Divide total connections by backend count [OK]

Common Mistakes:

• Multiplying instead of dividing
• Ignoring even distribution assumption
• Choosing total connections as answer

4. You configured a TCP Load Balancer but backend instances are not receiving traffic. What is a common misconfiguration to check?

medium

A. Backend instances lack proper health checks

B. Forwarding rule uses HTTP protocol instead of TCP

C. Backend instances are in different cloud provider

D. Load balancer IP is not public

Solution

1. Step 1: Check health checks configuration

   Load balancer only sends traffic to healthy backends. Missing or failing health checks cause no traffic routing.

2. Step 2: Verify backend health status

   Ensure health checks are properly configured and passing for backend instances.

3. Final Answer:

   Backend instances lack proper health checks -> Option A

4. Quick Check:

   Health checks enable traffic routing [OK]

Hint: Always verify backend health checks first [OK]

Common Mistakes:

• Assuming protocol mismatch blocks traffic
• Ignoring health check failures
• Thinking IP must be public for internal load balancer

5. You want to design a highly available TCP Load Balancer in GCP that handles millions of connections. Which combination ensures scalability and fault tolerance?

hard

A. Use a global HTTP(S) Load Balancer with TCP backend services

B. Deploy multiple zonal TCP Load Balancers without health checks to reduce latency

C. Use a single regional TCP Load Balancer with multiple backend instance groups and health checks

D. Configure a single backend instance with autoscaling but no load balancer

Solution

1. Step 1: Understand GCP TCP Load Balancer types

   Regional TCP Load Balancers distribute traffic across multiple backend instance groups within a region, supporting health checks and autoscaling.

2. Step 2: Evaluate scalability and fault tolerance

   Multiple backend groups with health checks ensure traffic only goes to healthy instances, enabling fault tolerance and scaling to millions of connections.

3. Final Answer:

   Use a single regional TCP Load Balancer with multiple backend instance groups and health checks -> Option C

4. Quick Check:

   Regional LB + backends + health checks = scalable & fault tolerant [OK]

Hint: Regional LB + health checks = scalable, fault tolerant [OK]

Common Mistakes:

• Ignoring health checks reduces reliability
• Using HTTP(S) LB for TCP traffic is incorrect
• Single backend instance limits scalability