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Network Fundamentals: Top Picks

Network Fundamentals

Firewall Topologies

In this section we are going to talk about the different ways a firewall can be set up. Depending on your needs, you can have a very simple firewal...
Network Fundamentals

Next-Gen Firewalls & Topologies. Designing & Bu...

Next-generation firewalls (NGFWs) and DMZ zones are two critical components of network security that work hand in hand to protect an organization's...
Network Fundamentals

Securing Your Home Network

In today's world, securing your home network is more important than ever. With the increasing number of cyberattacks, data breaches, and online fra...
Network Fundamentals

LAN Network Topologies

Network topologies can take a bit of time to understand when you're all new to this kind of cool stuff, but it's very important to fully understand...

Featured Subcategories:

Netflow Articles:

Netflow

Netflow vs SNMP. Two Different Approaches to Ne...

SNMP (Simple Network Management Protocol) and Netflow are both popular protocols with admins, prized for their ability to give visibility over the ...
Netflow

NetFlow Analyzer: Free Download, Step-by-Step I...

In our previous article we explained how a Netflow Analyzer can help you gain visibility into your user traffic, application traffic and data flows...
Netflow

Complete Guide to Netflow: How Netflow & its Co...

This article will cover the basics of Netflow, including its use cases, Netflow supported devices, Netflow history, and variants. We’ll also dive i...
Netflow

Netflow: Monitor Bandwidth & Network Utilizatio...

Monitoring network traffic & bandwidth usage via Netflow is mandatory for any type and size network. Gaining visibility into user traffic, appl...

Network Protocols:

Subnetting

IP Subnetting - Part 2: Subnet Masks & Their Ef...

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 o...
TCP - UDP Protocol Analysis

TCP Header Anaylsis - Section 5: TCP Window Siz...

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 ...
TCP - UDP Protocol Analysis

TCP Header Anaylsis - Section 2: TCP Sequence &...

This page will closely examine the Sequence and Acknowledgement numbers. The very purpose of their existence is related directly to the fact that t...
Domain Name System (DNS)

The DNS Protocol - Part 3: DNS Query Message Fo...

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....
TCP - UDP Protocol Analysis

UDP Protocol - Header

This article covers the UDP protocol. We examine the structure of the UDP header, the protocols that use UDP as a transport plus a lot more. Some ...
TCP - UDP Protocol Analysis

Transmission Control Protocol - Part 4: In-Dept...

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 mov...
TCP - UDP Protocol Analysis

TCP Header Anaylsis - Section 3: TCP Header Len...

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...
TCP - UDP Protocol Analysis

TCP Header Anaylsis - Section 4: TCP Flag Options

As we have seen in the previous pages, some TCP segments carry data while others are simple acknowledgements for previously received data. The popu...

STP/ICMP Protocols:

ICMP Protocol

ICMP Protocol - Part 4: Destination Unreachable...

The 'ICMP Destination unreachable' message is quite interesting, because it doesn't actually contain one message, but infact six! This means that t...
Spanning Tree Protocol (STP)

Spanning Tree Protocol – Part 1: Understand 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, s...
ICMP Protocol

ICMP Protocol - Part 5: Source Quench Message A...

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 workstatio...
ICMP Protocol

ICMP Protocol - Part 2: Echo / Echo Reply (Ping...

As mentioned in the previous page, an Echo is simply what we networking engineers call a 'ping'. The Echo Reply is, as most would guess,  the ...

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VLAN Networks

Dynamic VLANs

Dynamic VLANs were introduced to grant the flexibility and complexity(!) that Static VLANs did not provide. Dynamic VLANs are quite rare because of thei...
VLAN Networks

VLAN Security - Making the Most of VLANs

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...
VLAN Networks

VLANs - IEEE 802.1q Trunk Link Protocol Analysis

While the VLAN Tagging article briefly covered the IEEE 802.1q protocol this article will continue building upon it by further analyzing the IEEE 802.1q...
VLAN Networks

The VLAN Concept - Introduction to VLANs

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 Ne...

Routing

Introduction to Routing Protocols

Distance Vector, Link State RIP, IGRP, EIGRP, OSPF Routing protocols were created for routers. These protocols have been designed to allow the exchan...
Routing

The IP Routing Process - Step-by-Step Analysis

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 yo...
Routing

OSPF - Part 5: Analysis of OSPF Link State Update (L...

This article explains how OSPF uses Link State Advertisement (LSA) to exchange information about the network topology between routers. When a router rec...
Routing

Enhanced Interior Gateway Routing Protocol - EIGRP

Enhanced Interior Gateway Routing Protocol (EIGRP), similar to IGRP, is a Cisco proprietary routing protocol that is used to exchange routing informatio...

Network Address Translation - NAT

Static NAT - Part 2

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 ...
Network Address Translation - NAT

Dynamic NAT - Part 2

Our previous article, Dynamic NAT - Part 1, covered the basic idea of Dynamic Network Address Translation. We are now going to take a closer look at the...
Network Address Translation - NAT

Network Address Translation (NAT) Concepts

Before we dive into the deep waters of NAT, we need to make sure we understand exactly what NAT does. So let me give you the background of NAT, why it's...
Network Address Translation - NAT

Network Address Translation (NAT) Overload - Part 1

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 li...