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Network Fundamentals: Top Picks

Network Fundamentals
Network Switches are the evolution of Hubs and Repeaters, and enable the creation of networks by connecting multiple devices together. They are criti…
Network Fundamentals
A Denial of Service (DoS) attack is a malicious attempt to disrupt the normal functioning of a website, server or network by flooding it with traffic…
Network Fundamentals
Multicast is a communication method used in computer networking where data is sent from a single sender to a group of destination devices. In this m…
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…

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
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…
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…

Network Protocols:

IP Protocol
This article explains the 'Network-ID' and 'Host-ID' concept found in IP addressing and subnetting. We analyse the structure of IP addresses and netw…
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
This article shows the TCP Header and Segment. We explain where the TCP Header and Segment are located in an Ethernet frame and also briefly view the…
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…
Supernetting & CIDR
This articles build upon our previous pages covering  what is Supernetting (Route Summarization) & How Supernets Work and Supernetting In-De…
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 deal with the analysis of the DNS packets by examining how DNS messages are formatted and the options and variables they contain. T…
Subnetting
So we have covered to some depth the subnetting topic, but there is still much to learn ! We are going to explain here the available subnet masks and…

STP/ICMP Protocols:

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…
ICMP Protocol
The 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that the…
ICMP Protocol
The ICMP - Redirect Message is always sent from a gateway to the host and the example below will illustrate when this is used. Putting it simply (be…
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…

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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
The invention of VLANs was very much welcomed by all engineers and administrators, allowing them to extend, redesign and segment their existing network wi…
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
VLANs are usually created by the network administrator, assigning each port of every switch to a VLAN. Depending on the network infrastructure and securit…

Routing
This article explains how OSPF uses Link State Advertisement (LSA) to exchange information about the network topology between routers. When a router recei…
Routing
IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informati…
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…
Routing
Our previous article explained the purpose of Link State Update (LSU) packets and examined the Link State Advertisement (LSA) information contained within…

Network Address Translation - NAT
Dynamic NAT is the second NAT mode we're going to talk about. Dynamic NAT, like Static NAT, is not that common in smaller networks but you'll find it used…
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
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
In our previous article, Network Address Translation (NAT) Overload - Part 1, we explained what NAT Overload is and how it works. This page deals with the…