TCP/UDP Load Balancer (Layer 4) in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a TCP/UDP Load Balancer at Layer 4?

It is a network device that distributes incoming TCP or UDP traffic to backend servers based on IP address and port without inspecting the content of the packets.

intermediate

How does a Layer 4 Load Balancer differ from a Layer 7 Load Balancer?

Layer 4 Load Balancer routes traffic based on IP and port (transport layer), while Layer 7 Load Balancer routes based on application data like HTTP headers or URLs.

beginner

What are the benefits of using a TCP/UDP Load Balancer in GCP?

It provides high availability, scales traffic efficiently, supports both TCP and UDP protocols, and offers global or regional load balancing with health checks.

beginner

What is a health check in the context of a TCP/UDP Load Balancer?

A health check is a periodic test that verifies if backend servers are available and responsive to receive traffic, helping the load balancer avoid sending traffic to unhealthy servers.

intermediate

Why is session affinity less common in Layer 4 Load Balancers compared to Layer 7?

Because Layer 4 Load Balancers only see IP and port information, they have limited ability to track user sessions compared to Layer 7 which can use cookies or application data for affinity.

Which OSI layer does a TCP/UDP Load Balancer operate on?

A Layer 3 (Network Layer)

B Layer 7 (Application Layer)

C Layer 4 (Transport Layer)

D Layer 2 (Data Link Layer)

TCP/UDP Load Balancers operate at Layer 4, handling traffic based on IP addresses and ports.

What protocols does a Layer 4 Load Balancer typically support?

A DNS and DHCP

B HTTP and HTTPS

C FTP and SMTP

D TCP and UDP

Layer 4 Load Balancers support TCP and UDP protocols, which are transport layer protocols.

In GCP, what feature helps a TCP/UDP Load Balancer avoid sending traffic to a down server?

A Health Checks

B Cloud CDN

C Firewall Rules

D IAM Policies

Health Checks monitor backend server status to ensure traffic is only sent to healthy servers.

Which of these is NOT a characteristic of a Layer 4 Load Balancer?

A Routing based on IP and port

B Inspecting HTTP headers

C Supporting TCP and UDP traffic

D Providing high availability

Inspecting HTTP headers is done by Layer 7 Load Balancers, not Layer 4.

What is a common use case for a TCP/UDP Load Balancer in GCP?

A Balancing database or gaming server traffic

B Distributing web page requests based on URL

C Caching static content

D Managing user authentication

TCP/UDP Load Balancers are ideal for non-HTTP traffic like databases or gaming servers.

Explain how a TCP/UDP Load Balancer works and why it is useful in cloud environments like GCP.

Think about how traffic is split without looking inside the data.

Describe the differences between Layer 4 and Layer 7 load balancing and when you might choose each.

Consider what information each layer can see in the network stack.