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Troubleshooting Wireless Networks

  • network access control (NAC)

    Network access control (NAC), also called network admission control, is a method of bolstering the security of a proprietary network by restricting the availability of network resources to endpoint devices that comply with a defined security policy.... Continue Reading

  • Wireless network security testing

    The abundance of wireless devices is making wireless networks -- both authorized and unauthorized -- more common. Attack your own wireless networks to find vulnerabilities before malicious hackers do. Security testing expert Kevin Beaver covers the ... Continue Reading

  • Introduction to Network Protection - Protect Your Windows Network from Perimeter to Data, Chapter 1

    Introduction to Network Protection from 'Protect Your Windows Network from Perimeter to Data' by Jesper Johansson and Steve Riley explains how you can best protect your systems network by balancing security and usability/usefulness. Continue Reading

  • maximum transmission unit (MTU)

    A maximum transmission unit (MTU) is the largest size packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network such as the Internet. Continue Reading

  • maximum segment size (MSS)

    The maximum segment size (MSS) is the largest amount of data, specified in bytes, that a computer or communications device can handle in a single, unfragmented piece. Continue Reading

  • master

    A master, in a technological context, is a device that controls one or more other devices.Continue Reading

  • Understanding duplex conflicts

    What is duplex, and what is the difference between half and full duplex? What is a duplex mismatch? How can auto-negotiation help or hurt your network? How can you resolve duplex conflicts? Here's some help.Continue Reading

  • network analyzer (protocol analyzer or packet analyzer)

    A network analyzer is a combination of hardware and programming, or in some cases a stand-alone hardware device, that can be installed in a computer or network to enhance protection against malicious activity... (Continued)Continue Reading

  • FTAM (File Transfer Access Method)

    File Transfer Access Method (FTAM), also known as File Transfer Access and Management or Electronic File Transfer Access Method (EFTAM), is an ISO standard that specifies methods of transfering files between networked computers... (Continued)Continue Reading

  • QoS implementation basics

    In this response, Lindi Horton discusses some of the basics of implementing Quality of Service.Continue Reading

  • Wireless network troubleshooting

    Network operators often have the difficult task of troubleshooting wireless issues that arise not only on the wireless LAN but also with users and devices seeking access to it. Having knowledge of common hardware problems and configuration issues is...Continue Reading

  • Cellular data convergence: An introduction to wireless and 3G

    The world of wireless data capabilities on the carrier networks is seeing a tremendous amount of growth as it relates to standards and service offerings. In this tip, Robbie Harrell sorts out the alphabet soup of data capabilities being offered by ...Continue Reading

  • asymmetric communications

    In telecommunications, the term asymmetric (also asymmetrical or non-symmetrical) refers to any system in which the data speed or quantity differs in one direction as compared with the other direction, averaged over time.Continue Reading


    DARPANET (or DARPANet) is a term sometimes used for the ARPANET, the early network from which today's Internet evolved.Continue Reading

  • Appleshare

    The AppleShare protocol is a communications protocol from Apple Computer that allows client applications in a computer to exchange files with and request services from server programs in a computer network.Continue Reading

  • APPC (Advanced Program-to-Program Communication or LU 6.2)

    APPC (Advanced Program-to-Program Communication, sometimes called LU 6.2) is a communication protocol and programming interface standard that operates in the presentation layer and the session layer of the Open Systems Interconnection (OSI) ...Continue Reading

  • anycast

    In Internet Protocol Version 6 (IPv6), anycast is communication between a single sender and the nearest of several receivers in a group. The term exists in contradistinction to multicast, communication between a single sender and multiple receivers...Continue Reading

  • mail user agent (MUA)

    A mail user agent (MUA) is a program that allows you to receive and send e-mail messages; it's usually just called an e-mail program.Continue Reading

  • MAE

    A MAE (pronounced MAY), originally an abbreviation for Metropolitan Area Exchange and now a service mark of MCI WorldCom, is a major center in the United States for interconnecting traffic between Internet service providers (ISPs).Continue Reading

  • Logical Link Control layer (LCL layer)

    The Logical Link Control (LCL) layer is one of two sublayers of the Data-Link layer in the Open Systems Interconnection (OSI) model of communication. The LCL layer is concerned with managing traffic (flow and error control) over the physical medium.Continue Reading

  • collision

    In a half duplex Ethernet network, a collision is the result of two devices on the same network attempting to transmit data at exactly the same time.Continue Reading

  • wire speed

    Wire speed refers to the rate of data transfer a given telecommunication technology provides at the physical wire level.Continue Reading

  • network computer (NC)

    A network computer (NC) is a concept from Oracle and Sun Microsystems that describes a low-cost personal computer for business networks that, like the NetPC, would be configured with only essential equipment (including CD-ROM players, diskette ...Continue Reading

  • acoustic coupler

    An acoustic coupler is a hardware device that enables a modem (a device that converts signals from analog to digital and from digital back to analog) to connect to a voice circuit.Continue Reading

  • ACK

    In some digital communication protocols, ACK is the name of a signal that data has been received successfully (for example, with an acceptable number of errors).Continue Reading

  • BOOTP (Bootstrap Protocol)

    BOOTP (Bootstrap Protocol) is a protocol that lets a network user be automatically configured (receive an IP address) and have an operating system booted (initiated) without user involvement.Continue Reading

  • Jini

    Jini (pronounced "GEE-nee" like the Arabic word for "magician") is a network architecture concept that Sun Microsystems calls "spontaneous networking." Using Jini, users will be able to plug printers, storage devices, speakers or any kind of device...Continue Reading

  • jam

    In an Ethernet network, a jam is a signal from one device to all other devices that a collision has occurred. Specifically, the device was trying to send a frame while another device was also trying to put a frame on the line.Continue Reading

  • jabber (in networks)

    In networks, a jabber is any device that is handling electrical signals improperly, usually with negative results for the rest of the network.Continue Reading

  • Jabber

    Jabber is an initiative to produce an open source, XML-based instant messaging platform.Continue Reading

  • call failure rate (CFR)

    The call failure rate (CFR) is the percentage of calls to an ISP or any network provider that fail to get through. The CFR is commonly used as a statistical measure in assessing Internet service providers.Continue Reading

  • weighted fair queueing (WFQ)

    Weighted fair queueing (WFQ) is a method of automatically smoothing out the flow of data in packet-switched communication networks by sorting packets to minimize the average latency and prevent exaggerated discrepancies between the transmission ...Continue Reading

  • 10-high-day busy period (10HD busy period)

    In designing and assessing networks, the peak load is sometimes measured using the 10HD (10-high-day) busy period method.Continue Reading

  • 1000BASE-T

    1000BASE-T is Gigabit Ethernet (1 gigabit is 1000 megabits per second) on copper cables, using four pairs of Category 5 unshielded twisted pair to achieve the gigabit data rate.Continue Reading

  • OpenNMS (Open Network Management System)

    OpenNMS (Open Network Management System) is the first enterprise-grade network management platform developed under the open source model.Continue Reading

  • Novell Directory Services (NDS)

    Novell Directory Services (NDS) is a popular software product for managing access to computer resources and keeping track of the users of a network, such as a company's intranet, from a single point of administration.Continue Reading

  • network operations center (NOC)

    A network operations center (NOC) is a place from which administrators supervise, monitor and maintain a telecommunications network.Continue Reading

  • network access server (NAS)

    A network access server (NAS) is a computer server that enables an independent service provider (ISP) to provide connected customers with Internet access.Continue Reading

  • NetWare

    NetWare, made by Novell, is a widely-installed network server operating system.Continue Reading

  • N1

    N1 is Sun Microsystems' strategy for making a network environment as easy to manage as a single machine.Continue Reading

  • multistation access unit (MSAU)

    A multistation access unit (MSAU) is a hub or concentrator that connects a group of computers ('nodes' in network terminology) to a token ring local area network.Continue Reading

  • loopback test

    A loopback test is a test in which a signal in sent from a communications device and returned (looped back) to it as a way to determine whether the device is working right or as a way to pin down a failing node in a network.Continue Reading

  • loopback

    In telephone systems, a loopback is a test signal sent to a network destination that is returned as received to the originator. The returned signal may help diagnose a problem.Continue Reading

  • Kbps (kilobits per second)

    In the U.S., Kbps stands for kilobits per second (thousands of bits per second) and is a measure of bandwidth (the amount of data that can flow in a given time) on a data transmission medium.Continue Reading

  • null modem

    A null modem cable allows you to connect your PC to another nearby PC or serial device using its modem protocol.Continue Reading

  • forest-and-tree model

    The forest-and-tree model is a logical structure for interconnecting multiple network domains in Windows 2000 and later operating systems.Continue Reading

  • VRRP (Virtual Router Redundancy Protocol)

    VRRP (Virtual Router Redundancy Protocol) is an Internet protocol that provides a way to have one or more backup routers when using a statically configured router on a local area network (LAN).Continue Reading

  • virtual network computing (VNC)

    Virtual network computing (VNC) is a type of remote-control software that makes it possible to control another computer over a network connection...Continue Reading

  • terminal emulation

    Terminal emulation is the ability to make one computer terminal, typically a PC, appear to look like another, usually older type of terminal so that a user can access programs originally written to communicate with the other terminal type.Continue Reading

  • port number

    A port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server.Continue Reading

  • network tracking tool (network device management program)

    A network tracking tool, also called a network device management program, is a program that helps a network administrator keep track of moves, additions, and changes (known as MACs) to the hardware infrastructure of a network.Continue Reading

  • audible ring

    In a telephone system, an audible ring is the tone that is returned from the called party's switching device and heard by the caller. This tone indicates to the caller that the desired party is being rung.Continue Reading

  • Guide to network security

    This guide introduces you to the main components in whole network security. You'll find articles, tutorials, tips, tools, white papers and more to pump up your network security quickly.Continue Reading

  • Telnet

    What is Telnet? Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers.Continue Reading

  • Network Virtualization, Chapter 3: A basic virtualized enterprise

    In this excerpt from Network Virtualization by Victor Moreno and Kumar Reddy, learn the technical requirements posed by the need to virtualize the network, as well as an architectural framework comprised of the functional areas necessary to ...Continue Reading

  • terminal proxy server (TPS)

    A terminal proxy server (TPS) is a program that acts as an interface for voice over Internet Protocol (VoIP) telephone sets... (Continued)Continue Reading

  • Open source network tools

    Some of the most commonly used, enterprise-ready open source tools are used for networking applications; likewise, many networking tasks can be accomplished quickly and cheaply using open source tools. In this guide, we present advice and resources ...Continue Reading

  • NetDirector, an introduction: Free, simple server management

    NetDirector provides a free, customizable, easy way for network and systems administrators to configure network services and manage groups of Linux, Solaris, or BSD servers. The open source tool is also part of a movement towards greater ...Continue Reading

  • Manufacturing Message Specification (MMS)

    The Manufacturing Message Specification (MMS) is an international standard that defines the ways in which control information is transferred among intelligent devices and systems such as computers and robots... (Continued)Continue Reading

  • branch office box (BOB)

    A Branch Office Box (BOB) is a server appliance that has been optimized to provide distributed support for simple utility functions that are required locally but are difficult to provide over a WAN... (Continued)Continue Reading

  • VPN appliance

    A VPN (virtual private network) appliance is a network device equipped with enhanced security features... (Continued)Continue Reading

  • common channel signaling (CCS)

    Common channel signaling (CCS) is signaling (for example, in a T-carrier system line) in which a group of voice-and-data channels share a separate channel that is used only for control signals.Continue Reading

  • channel-associated signaling (CAS)

    Channel-associated signaling (CAS) is signaling (for example, in a T-carrier system line) in which control signals, such as those for synchronizing and bounding frames, are carried in the same channels as voice and data signals... (Continued)Continue Reading

  • fax

    A fax (short for facsimile and sometimes called telecopying) is the telephonic transmission of scanned-in printed material (text or images), usually to a telephone number associated with a printer or other output device.Continue Reading

  • Routing versus routed protocols and the CCNA

    Many networking professionals don't really know what a routing protocol is or does. There are those who also couldn't tell you the difference between a routing protocol and a routed protocol. If you are working as a network engineer or preparing to ...Continue Reading

  • OpenNMS, an introduction: Affordable network management

    Open source expert Maria Winslow brings network managers up to speed about the free open source enterprise-grade network-management system OpenNMS.Continue Reading

  • Crash Course: Security patching and upgrades

    Keeping your network safe and secure is a never ending job. Just when you think your defenses can't get any better, a new worm hits the net or a flaw is detected in your hardware. That's where security patching and upgrades come in. Get the latest ...Continue Reading

  • Wireless networking (CWNA)

    Do you think you know a lot about wireless networking? Are you interested in taking the Certified Wireless Network Administrator (CWNA) exam? Test your knowledge with our 13-question quiz on wireless networking!Continue Reading

  • Basic Object Configuration, chapter 2 of 'Pro Nagios 2.0'

    Get started on the basics of configuring your Nagios server to monitor hosts and services. Learn the differences between Nagios object types and their capabilities.Continue Reading

  • firehose effect

    A firehose effect occurs in a network when the source (transmitting) computer or terminal sends data too fast for a destination (receiving) computer or terminal to deal with it. The term comes from the analogy between a data stream and the flow of ...Continue Reading

  • Ethernet point-of-presence (EPOP)

    Ethernet point-of-presence (EPOP) is a technology developed by Level 3 Communications that provides widespread access to broadband networks. As a large network increases its bandwidth, it can include large and expanding groups of subscribers. This ...Continue Reading

  • Content Delivery Networking: an introduction

    Doug Downer gives an overview of Content Delivery Network (CDN) technology and its components, which bring together the functionality of file access, caching, multimedia delivery and application processing.Continue Reading

  • capacity planning

    In information technology, capacity planning is the science and art of estimating the space, computer hardware, software and connection infrastructure resources that will be needed over some future period of time.Continue Reading

  • isochronous

    In information technology, isochronous (from the Greek "equal" and "time"; pronounced "eye-SAH-krun-us") pertains to processes that require timing coordination to be successful, such as voice and digital video transmission.Continue Reading

  • Introduction to Ethical Hacking - from Hacking For Dummies

    This chapter from Hacking For Dummies by Kevin Beaver helps security professionals understand how malicious users think and work, enabling them to defend their systems against attacks and to identify security vulnerabilities.Continue Reading

  • H.323

    H.323 is a standard approved by the International Telecommunication Union (ITU) in 1996 to promote compatibility in videoconference transmissions over IP networks.Continue Reading

  • multicast

    Multicast is communication between a single sender and multiple receivers on a network.Continue Reading

  • 802.11a

    802.11a is one of several specifications in the 802.11 family applicable to wireless local area networks (wireless LANs or WLANs).Continue Reading

  • Clientless VPN: Artful misnomer, useful technology

    They may not be completely clientless, but clientless VPNs can provide secure, user-friendly and largely affordable solutions to enable remote access over the Internet.Continue Reading

  • Securing your Layer 2 network: Don't overlook the basics

    Before dropping substantial cash on a fancy surveillance system, most sensible home owners would ensure that their doors and windows were locked. Similarly, there are simple security measures you can take to configure your systems for Layer 2 ...Continue Reading

  • terminal

    In data communications, a terminal is any device that terminates one end (sender or receiver) of a communicated signal.Continue Reading

  • Guide to networking with Windows

    This guide explains everything you need to know about networking with Windows.Continue Reading

  • Fundamentals of IP - Chapter 5 of CCNA Intro Exam Certification Guide

    Chapter 5 of "CCNA Intro Exam Certification Guide" by Wendell Odom describes the core concepts behind OSI Layer 3. Because CCNA focuses on TCP/IP, you also will learn about the main Layer 3 protocol used by TCP/IP -- namely, the Internet Protocol (...Continue Reading

  • handshaking

    In telephone communication, handshaking is the exchange of information between two modems and the resulting agreement about which protocol to use that precedes each telephone connection.Continue Reading

  • Crash Course: Protocol analysis

    Analyzing your network is essential to keep it running smoothly and safely. This collection of articles, many contributed by Laura Chappell, shows you the ins and outs.Continue Reading

  • home server

    A home server is a computer that functions as a server in a client-server home network.Continue Reading

  • Uuencode (Uuencode/Uudecode)

    Uuencode (also called Uuencode/Uudecode) is a popular utility for encoding and decoding files exchanged between users or systems in a network.Continue Reading

  • CompTIA A+ resources

    What are the benefits of becoming A+ certified? And what should you study before taking the exam? These handy resources supplied by will help you on your way to passing the A+ exam.Continue Reading

  • Crash Course: Networking certifications

    If you've been in the networking field for even a short while, you've undoubtedly realized the importance of certifications to your career prospects. But there are a slew of certs out there and figuring out which ones are right for you is hardly an ...Continue Reading

  • 802.11 Learning Guide

    802.11 is perhaps the fastest-changing network protocol around. We've gathered a wealth of information to get you up-to-speed quickly on the various specifications. Learn about all the 802.11 wireless LAN (WLAN) specifications in this learning guide.Continue Reading

  • wink

    In telecommunications, a wink is a signal in the form of a brief interruption in an otherwise continuous signal.Continue Reading

  • cloud

    In telecommunications, a cloud is the unpredictable part of any network through which data passes between two end points.Continue Reading

  • OSI model: Crash Course

    The OSI model is the conceptual backbone of most enterprise networks, but do you remember all the details? Read our rundown of the OSI model and what all those layers do.Continue Reading

  • Crash Course: Firewalls

    Firewalls aren't as simple as they used to be. Use our Crash Course to learn the latest and make sure your firewall is right for your network.Continue Reading

  • Real-world network management

    Managing today's complex networks is arguably the most challenging part of a network professional's job. These multimedia resources show you how some real companies solved their management problems and outline best practices for applying good ...Continue Reading

  • port

    On computer and telecommunication devices, a port (noun) is generally a specific place for being physically connected to some other device, usually with a socket and plug of some kind.Continue Reading

  • acceleration hardware

    Acceleration hardware is a general term that refers to devices that speed up data communications, storage and retrieval, encryption and decryption, mathematical operations, graphics, and Web page viewing. Acceleration hardware can consist of an ...Continue Reading

  • Crash Course: Windows networking

    Love it or hate it, part of every net admin's job is making your infrastructure work with Microsoft software. In this Windows networking Crash Course, we've assembled our best tips and tricks to make your job easier.Continue Reading

  • encoding and decoding

    Encoding is the process of putting a sequence of characters (letters, numbers, punctuation, and certain symbols) into a specialized digital format for efficient transmission or transfer. Decoding is the opposite process -- the conversion of a ...Continue Reading

  • Turtle Firewall

    Turtle Firewall is an open source firewall program written in Perl that supports Linux Kernels 2.4.x and iptables. Turtle Firewall was written by Andrea Frigido of Frisoft, and is available under the GNU Public License (GPL) .Continue Reading