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Subnetting

IP Subnet Calculator

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 desired IP Address and Subnet Mask below and press Ca...

ICMP Protocol

ICMP Protocol - Part 7: Time Exceeded Message A...

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 familiar with the IP header within a packet. Our...

Cisco Switches

Cisco Catalyst 4500 Series Zero-Downtime IOS Up...

The Supervisor Engine is the heart of the Cisco Catalyst 4500 and 6500 series switches. It is the equivalent of an engine in a car. Every packet that enters or exits your switch passes through the ...

Cisco Routers

Configuring NTP on a Cisco Router (NTP Client a...

Network Time Protocol (NTP) is a vital service not only for Cisco devices but almost every network device. Any computer-based device needs to be accurately synchronised with a reliable time source ...

VPN Services & Guides

VPN Hotspot - How to Stay Safe on Public & Gues...

Is Guest WiFi Safe? It’s hard to go to a pub, café, or hotel these days without running into public or guest WiFi. In many cases, an internet connection can feel like a necessity – keeping up with...

Cisco CallManager-CCME

Cisco SPA525G / SPA525G2 User Guide Free Download

Available as a free download in our Cisco Small Business Series Product Datasheet section is the Cisco SPA525G / SPA525G2 User Guide. This 68 page user guide contains all the necessary information ...

Windows Servers

Introduction To Windows Server 2012 R2 Virtuali...

FREE Hyper-V & VMware Backup: FREE for Firewall.cx readers for a Limited Time! Download Now! Virtualization is an abstraction layer that creates separate distinct virtual environme...

Ethernet Protocol, CSMA/CD, Collisions

The IEEE 802.3 SNAP Frame Format

While the original 802.3 specification worked well, the IEEE realized that some upper layer protocols required an Ethertype to work properly. For example, TCP/IP uses the Ethertype to differentiate...

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, study, and in various other areas of life. Unless w...

Windows Servers

How to Enable & Configure Shadow Copy for Share...

When you shadow copy a disk volume, you are actually generating a snapshot of the changes made to the folders and files within the disk volume at a certain point in time. Windows 2012 R2 shadow cop...

Network Protocols

ISDN Layers, Protocols & Components

Our previous article was an Introduction To The ISDN Protocol. This article dives a bit deeper by examining ISDN Layers, Protocols & Components. ISDN uses circuit-switching to establish a phys...

Ethernet Protocol, CSMA/CD, Collisions

Troubleshooting techniques for Fast Ethernet

This page will primarily discuss problems unique to Fast Ethernet. The Collision Domain Incompatible Ethernet Jabber Auto-negotiation Priorities And Alternatives Incompatible Cabling Specific...