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Network Fundamentals: Top Picks

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
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
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
The term "Broadcast" is used very frequently in the networking world . You will see it in most networking books and articles, or see it happening on…

Featured Subcategories:

Netflow Articles:

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…
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…

Network Protocols:

Supernetting & CIDR
Our previous article served as an introduction to Supernetting, also known as Route Summarization. We covered the concept of Supernetting, how it wor…
Domain Name System (DNS)
The previous article covered the DNS Query message formats. In the article we analysed them in great detail and showed how various options are select…
TCP - UDP Protocol Analysis
This article is an introduction to the 7-page TCP Header analysis section that follows. We briefly view each section of the TCP Header and then move…
TCP - UDP Protocol Analysis
The third field under close examination is the TCP Header length. There really isn't that much to say about the Header length other than to explain w…
Subnetting
Routing and Communication between subnets is the main topic here. This article analyses communications between subnets. We provide examples on differ…
TCP - UDP Protocol Analysis
This section contains one of the most well-known fields in the TCP header, the Source and Destination port numbers. These fields are used to specify…
TCP - UDP Protocol Analysis
Our fifth section contains some very interesting fields that are used by the TCP transport protocol. We see how TCP helps control how much data is tr…
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)
In this article we will examine the Spanning Tree Bridge ID structure, explain why it has increments of 4096, how VLAN information is embedded (for P…
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…
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…

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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…
VLAN Networks
Deciding whether to use ISL or IEEE 802.1q to power your trunk links can be quite confusing if you cannot identify the advantages and disadvantages of eac…
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
We hear about them everywhere, vendors around the world are constantly trying to push them into every type of network and as a result, the Local Area Netw…

Routing
We are going to analyse what happens when routing occurs on a network (IP routing process). When I was new to the networking area, I thought that all you…
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
IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance-vector routing protocol used in enterprise networks to exchange routing informati…
Routing
This is the thrid article of our 6-part OSPF series (see below) that describes how OSPF routers perform neighbor relationship and adjacency. We’ll examine…

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
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…
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…
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…