1.6 Network Architecture

Question 1

What are the three layers in a three-tiered network architecture?

Answer 1

Core, Distribution, and Access layers.

• Core [downtown]: Centralized resources like servers and databases
• Distribution [highways]: Connects access layer to the core, provides redundancy; communication between access switches; manage the path to the end users
• Access [local roads]: Connects end users to the network; end stations, printers, etc.

📌 Transcript: “This starts with the core… the distribution layer… an access layer…” (0:12–1:00)

Question 2

What is the function of the core layer in a three-tiered architecture?

Answer 2

Hosts critical resources such as servers, applications, and databases.

Transcript: “Our servers, our applications… contained within the core…” (0:15–0:27)

Question 3

What role does the distribution layer play in the three-tier model?

Answer 3

It connects the access layer to the core, often with redundancy, and handles routing between subnets.

Transcript: “Midpoint between the users and those core resources…” (0:30–0:42)

Question 4

What is the function of the access layer in enterprise networking?

Answer 4

Provides direct connectivity for end-user devices to the network.

Transcript: “Switches… close to the user… allows us to connect to the distribution…” (0:47–1:00)

Question 5

What is the purpose of using multiple links between layers in a three-tiered architecture?

Answer 5

To provide redundancy, allowing alternative paths if one link fails.

Transcript: “You might even find multiple links… if one component happens to fail…” (2:04–2:17)

Question 6

What is a collapsed core architecture, and how is it different from a three-tier model?

Answer 6

It combines the core and distribution layers into one, reducing complexity and cost but with less redundancy.

Transcript: “A two-tier architecture that combines the core and distribution…” (2:48–3:23)

Question 7

What is east-west traffic in a data center?

Answer 7

Traffic that stays within the same data center—e.g., between servers.

Transcript: “Origination and destination… is all within the same data center…” (3:31–3:51)

Question 8

What is north-south traffic in a data center?

Answer 8

Traffic entering or leaving the data center—e.g., from or to the internet.

Transcript: “Traffic… leaving the data center or… coming into the data center…” (3:55–4:16)

Question 9

How does security posture differ between east-west and north-south traffic?

Answer 9

North-south traffic requires stricter security since it crosses trust boundaries; east-west traffic stays internal and is easier to manage.

Transcript: “Different security posture… we really don’t know where this traffic is going…” (4:04–4:14)