Our sister site, Server Fault, has a wiki of “canonical questions” that provide comprehensive answers to the most-often asked questions. We decided to create a similar list of questions and answers for Network Engineering. The questions and answers provide a single resource that visitors and members alike can get their most common questions answered.

To that end, I’ve compiled a list of questions that cover the most popular topics on Network Engineering. This is just my opinion, so feel free to recommend other questions (or categories) to be included.

OSI and TCP/IP Models

OSI Model and Networking Protocols Relationship

What is a "Layer 3 Switch"?

OSI layer : Ethernet and IP address

Do OSI and TCP/IP models use the same protocols?

Where do the layers of the OSI Model operate in the operating system??

Cabling (copper and fiber optics)

Is 30 Mbit/s fibre faster than 30 Mbit/s copper?

Speed benefits when switching from 1Gb copper LAN to Fiber Optic

What's the difference between an Ethernet cable and a UTP cable?

Minimum Ethernet Cable Length?

The maximum length of CAT6 for intranet network?

When to choose fiber instead of twisted pair (copper)

Multi-Mode and Single-Mode Fiber Differences

Speed of Light in Copper VS Fiber - Why is Fiber Better?


Why do we still use Ethernet?

Does having a longer Ethernet cable slow your connection?

Why was the MTU size for ethernet frames calculated as 1500 bytes?

Jumbo Ethernet Frame Deployment


Is it safe to use any wifi channel in the 2.4GHz band?

How do you prevent rogue wireless access points on a network?

Why does WLAN use Collision Avoidance and not Collison detection?

How does a WiFi range extender work?

omnidirectional antennas and the dipole antenna

Wireless Controller based vs Non-controller based

MAC (Layer 2) Addressing

How does a switch learn a switch table?

Why does ipv6 specify 128 bit address, when there are only 48 bits in MAC addresses?

Reason for both a MAC and an IP address

Does the source MAC address of a frame change when it passes through several switches?

VLANS and Trunking

Introductory level explanation of VLANs

Why and how are Ethernet Vlans tagged?

Difference between Subnet and VLAN?

IP Addressing

How do you calculate the prefix, network, subnet, and host numbers?

Why do we need IPv6?

What stops someone from configuring their network with IP addresses they do not own?

Why are there 3 ranges of private IPv4 addresses?


Why do we need a 3-way handshake? Why not just 2-way?

Why only port 80 for web services?

PING port number?

What do TCP/UDP add to "raw ip"?


Are CoS and QoS ever interchangeable?

Implementing Cisco QoS model to end users


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