Understand TCP/IP stack addressing and data flow

When you learn about networking, among the most fundamental topics are the layered models (OSI and TCP/IP). For a successful exam, it’s essential to know them and the related TCP/IP protocol stack. Some layers are even more important than others. Let’s see them:

Network Access Layer: The main focus at this layer will be on Ethernet addressing. You should understand the following about media access control (MAC) addresses:

MAC address structure and representation: 48 bits represented as 12 hexadecimal digits

MAC addressing on the local network: Any two hosts/nodes on an Ethernet network communicate using MAC addresses. Understand how ARP works and how a host keeps an ARP cache/table

Switches and MAC addresses: A basic understanding of the MAC address table or Content Addressable Memory (CAM) table, and how a switch builds and uses it to forward and filter traffic

Internet Layer: The tests will all have questions about Internet Protocol (IP) addressing. These include:

IPv4 addressing: Know the reserved addresses and understand what the subnet mask does

IPv6 addressing: Know the different address types (global, link local, unique local and so on) and addressing modes (unicast, multicast, anycast)
Spend some time getting familiar with subnetting concepts as it’s almost certain at least one question about subnetting, even more. Another task in this layer is routing: be familiar with static and dynamic routing concepts and the structure of the routing table.

Transport Layer: Know the characteristics of TCP and UDP. Be familiar with some of the common port numbers for well-known services like Telnet (23), HTTP (80), HTTPS (443) and others.