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Network Fundamentals: Top Picks

Network Fundamentals
A MAC address, or Media Access Control address, is a unique identifier assigned to a network interface controller (NIC) for use as a network addres…
Network Fundamentals
Content switches (also sometimes called application switches) is a class of network device that is becoming increasingly common in medium to large si…
Network Fundamentals
Unicast is a communication method used in computer networking where data is sent from a single sender to a specific destination device. In this…
Network Fundamentals
A long-long time ago (not long ago in earth time) 100 Mbps was THE technology. 100 Mbps uplinks bundled with ether-channel was the ultimate uplink te…

Featured Subcategories:

Netflow Articles:

Netflow
SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ne…
Netflow
In our previous article we explained how a Netflow Analyzer can help you gain visibility into your user traffic, application traffic and data flows w…
Netflow
This article will cover the basics of Netflow, including its use cases, Netflow supported devices, Netflow history, and variants. We’ll also dive int…
Netflow
Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, applic…

Network Protocols:

Supernetting & CIDR
Supernetting is the opposite of of subnetting, and is also known as route aggregation or CIDR (Classless Inter-Domain Routing). Supernetting is a tec…
TCP - UDP Protocol Analysis
Understanding how each protocol fits into the OSI Model is essential for any network engineer. This page analyses how TCP is classified as a 'transpo…
Subnetting
There is always that day when you are called upon to provide a solution to a network problem. The number of problems that can occur in a network are…
Domain Name System (DNS)
This section will help you understand how the DNS queries work on the Internet and your home network. There are two ways to use the domain name syste…
Subnetting
There are a few different ways to approach subnetting and it can get confusing because of the complexity of some subnets and the flexibility they off…
TCP - UDP Protocol Analysis
The TCP Options (MSS, Window Scaling, Selective Acknowledgements, Timestamps, Nop) are located at the end of the TCP Header which is also why they ar…
Domain Name System (DNS)
This section will deal with the analysis of the DNS packets by examining how DNS messages are formatted and the options and variables they contain. T…
Subnetting
This free online Subnet Calculator provides a fast and easy way to calculate all aspects of any IP Address and Subnet Mask. Simply enter your desir…

STP/ICMP Protocols:

ICMP Protocol
The ICMP - Source Quench message is one that can be generated by either a gateway or host. You won't see any such message pop up on your workstation…
ICMP Protocol
The ICMP - Time Exceeded message is one which is usually created by gateways or routers. In order to fully understand this ICMP message, you must be…
Spanning Tree Protocol (STP)
One of the most used terms in network is LAN (Local Area Network). It’s a form of network that we encounter in our daily lives, at home, at work, stu…
Spanning Tree Protocol (STP)
Spanning Tree Protocol, Rapid STP port costs and port states are an essential part of the STP algorithm that affect how STP decides to forward or blo…

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VLAN Networks
VTP (VLAN Trunking Protocol) pruning is a feature that is used in Cisco switches to reduce unnecessary traffic in VLAN (Virtual Local Area Network) trunks…
VLAN Networks
It's easy to see why virtual LANs have become extremely popular on networks of all sizes. In practical terms, multiple VLANs are pretty much the same as h…
VLAN Networks
We mentioned that Trunk Links are designed to pass frames (packets) from all VLANs, allowing us to connect multiple switches together and independently co…
VLAN Networks
Dynamic VLANs were introduced to grant the flexibility and complexity(!) that Static VLANs did not provide. Dynamic VLANs are quite rare because of their…

Routing
Routing Information Protocol (RIP) is a distance-vector routing protocol that is commonly used in small to medium-sized networks. It is one of the o…
Routing
Hybrid routing protocols are a combination of distance-vector and link-state routing protocols, and are used to provide a more efficient and scalabl…
Routing
Enhanced Interior Gateway Routing Protocol (EIGRP), similar to IGRP, is a Cisco proprietary routing protocol that is used to exchange routing information…
Routing
This article covers basic OSPF concepts and operation. We explain how OSPF works, how OSPF tables are built on an OSPF-enabled router and their purpose (N…

Network Address Translation - NAT
NAT Overload is the most common NAT method used throughout all networks that connect to the Internet. This is because of the way it functions and the limi…
Network Address Translation - NAT
Static NAT (also called inbound mapping) is the first mode we're going to talk about and also happens to be the most uncommon between smaller networks. S…
Network Address Translation - NAT
After that simple and informative introduction to the NAT concept, it's time to find out more about how it works and this is where the NAT table comes in…
Network Address Translation - NAT
The previous page (Static NAT - Part 1) helped us understand what exactly happens with Static NAT and how it works, and we saw a few examples of how to us…