Module Review

In this module, we climbed into the virtualized stratosphere:

  1. Virtual Private Cloud (VPC): How cloud providers offer isolated networks with private subnets, gateways, and routing tables.
  2. SDN: The separation of the Control Plane (central brain) from the Data Plane (forwarding hardware).
  3. NFV: Replacing expensive proprietary hardware with virtualized software (VNFs) running on standard servers.
  4. Load Balancing: Distributing traffic at Layer 4 or Layer 7 using algorithms like Round Robin to ensure high availability.
  5. CDN: Reducing global latency by caching content at Edge Locations near the end-user.

1. Flash Quiz

1. What is the difference between a Security Group and a NACL?

  • A Security Group acts at the Instance level and is stateful; a NACL (Network ACL) acts at the Subnet level and is stateless.

2. In SDN, which plane is responsible for making the actual forwarding decisions and is typically centralized in a controller?

  • The Control Plane.

3. What is a VNF in the context of NFV?

  • A Virtual Network Function (a software version of a firewall, router, or load balancer).

4. Which load balancing algorithm ensures that a user with a specific IP always hits the same server?

  • IP Hashing (Session Stickiness).

5. How does a CDN improve user experience for a website with a global audience?

  • It caches static content (images, JS) at Edge Locations geographically close to the users, which reduces physical distance and therefore reduces latency.

2. What’s Next?

We have reached the home stretch! In the final module, we focus on the “Survival Skills” of a network engineer: Reliability, Quality of Service (QoS), and Monitoring/Troubleshooting.