Problem solve
Get help with specific problems with your technologies, process and projects.
Problem solve
Get help with specific problems with your technologies, process and projects.
Half duplex vs. full duplex Ethernet 10BASE-T topologies
Ever wonder why half duplex Ethernet 10BASE-T topologies have a slower data transmission rate than full duplex Ethernet 10BASE-Ttopologies? Find out in this expert response by Lindi Horton. Continue Reading
What download speed will I get with a bandwidth of 1 MBPS?
Wondering what kind of download speed you can get with a bandwidth of 1 MBPS? Our expert, Lindi Horton can give you the lowdown on the download. Continue Reading
Cisco IOS IP routing: Static routes
Whether you are a network engineer or a student preparing for Cisco certification, it's important to understand how routers work. In this series on Cisco IOS IP routing, David Davis explains the differences between static and dynamic routing and ... Continue Reading
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IP addressing and subnetting: Calculate a subnet mask using the subnet's formula
IP addressing and subnetting are an important part of networks. Learn how the subnet's formula works and why it's important to know how to calculate the subnet mask "longhand." Continue Reading
System engineer vs. network administrator
Our Cisco certifications expert, David Minutella, answers what the responsibilities of a system engineer and network administrator are and what makes the two jobs different. Continue Reading
How IPsec provides secure communications
IPsec provides secure site-to-site VPNs, remote access and host-to-host communication. In this tip, we peek inside the tunnel and examine how IPsec works.Continue Reading
VPN client alternatives: Layer 2 Tunneling Protocol (L2TP) over IPsec
This month, Lisa Phifer discusses a robust VPN client alternative: Layer 2 Tunneling Protocol (L2TP) over IPsec.Continue Reading
Network test plan: Checklist for architecture changes
For every change you make to your network architecture, you should have a test plan and a backout plan. In this tip, learn how to build a test plan and review a sample checklist of things to include.Continue Reading
How SSL and TLS secure network transactions
SSL and TLS are protocols that were developed primarily to protect Web transactions, but they can be used to protect any type of network traffic that utilizes TCP at the transport layer, including the popular SSL VPN. In this tip, learn how SSL and ...Continue Reading
Router Expert: Building a WLAN proxy server, DHCP services: Part 1
Router expert Michael Martin discusses DHCP implementation options and provides sample configurations to support various SSID network models in this continuation of his series on building a WLAN proxy server.Continue Reading
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What to do when your server goes down
When a server goes down at a particular time every night without the prompt of a virus, our expert, Puneet Mehta, can tell you what the problem is and what you can do to avoid it.Continue Reading
IP addressing and subnetting: What network administrators need to know
IP addressing and subnetting are an important part of networks. Learn about how IP addresses work, subnet masks, classful vs. classless IP addresses, default gateways and more.Continue Reading
The most commonly used network operating system
In this Q&A, Lindi Horton answers the question "What network operating system is more currently and commonly used?"Continue Reading
Network cabling documentation
Network cabling documentation with dedicated documenation software can keep your cables from becoming a big mess.Continue Reading
OSI: Securing the stack, Layer 2 -- Understanding the role of ARP
Security expert Michael Gregg continues his layer-by-layer discussion of OSI model network security with this tip on the vulnerabilities present in Layer 2, the Data Link Layer, and specifically addresses the Address Resolution Protocol.Continue Reading
How round-trip time and limiting data rate impact network performance
This tip reviews how network parameters such as round-trip time and limiting data rate affect network performance.Continue Reading
OSI: Securing the stack, Layer 1 -- Physical security threats
Security expert Michael Gregg kicks off his layer-by-layer discussion of OSI model network security with this tip on securing Layer 1 against physical security threats.Continue Reading
Duplex mismatch
What is duplex, and what is the difference between half and full duplex? What is a duplex mismatch? How can autonegotiation help or hurt your network? How can you resolve duplex conflicts? In this tip, David Davis helps networking engineers and ...Continue Reading
IPSec and NAT incompatibility
Learn why Authentication Header (AH) doesn't work with Network Address Translation (NAT) or Port Address Translation (PAT) and that Encapsulating Security Payload (ESP) is also incompatible with PAT.Continue Reading
Wireless LAN setup for hotels
Phifer discusses the requirements for WLAN setups in hotels.Continue Reading
Multicasting on a wireless network
In this response, Phifer discusses multicasting on a wireless network.Continue Reading
VPNs for disaster recovery: IPsec vs. SSL
Using a VPN as a failover mechanism when a primary communications link may be unavailable due to a disaster can be a smart move -- as well as an easy one to implement. In this tip, learn about the pros and cons of IPsec and SSL VPN options for ...Continue Reading
Troubleshooting wireless networks: A systematic approach
Troubleshooting wireless networks can take up a lot of time for network operations staff with a wireless LAN (WLAN) environment. Wireless guru Lisa Phifer discusses the tools and processes involved and breaks down how to approach and resolve ...Continue Reading
DNS for a wireless network: Router Expert
DNS services are essential for building a secure wireless LAN. Our Router Expert provides complete instructions for setting up a DNS server, including implementing BIND, configuring a non-authoritative server and creating zone files.Continue Reading
T1 vs. VoIP for branch office connectivity
Learn how to decide between a T1, fractional T1 and VoIP for connecting branch offices.Continue Reading
WAN optimization and bottlenecks: Is the WAN really the weakest link?
"How much traffic" is no longer a good enough measure of WAN bandwidth. In this tip, Carrie Higbie looks at how today's ever-increasing expectations for data transfer rates require increased attention to WAN optimization, and suggests how ...Continue Reading
Duplex mismatch: Why duplex conflicts plague the network, part 1
Duplex mismatch problems -- caused by two ends of the Ethernet attempting a full-duplex connection, resulting in packet loss -- simply will not go away. After a decade of plaguing IP networks, duplex conflicts still seem to be the single worst ...Continue Reading
Security and the TCP/IP stack
Each layer of TCP/IP has security mechanisms, protocols, and applications. This tip describes the more popular ones that are associated with each layer of TCP/IP.Continue Reading
Five steps to stamp out unsafe Wi-Fi use
Lisa Phifer helps dispel the top myths of wireless security and explains five steps that network administrators can take to lead their users toward safer Wi-Fi usage.Continue Reading
SMB wireless LAN setup
Advice for setting up a WLAN for a SMB.Continue Reading
Reducing false positives in network monitoring
Network managers need to be aware of the importance of choosing the right tool to monitor their system's internal counters. In this tip, Brien Posey narrows in on alert mechanisms for Windows servers and helps you understand how to reduce false ...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
Binary-to-decimal conversion
Binary to decimal conversion is explained in this tip on how a network device uses its IP address, subnet mask and default gateway information.Continue Reading
IEEE 802.3at: Power over Ethernet plus
802.3af Power over Ethernet (PoE) has been widely adopted for powering VoIP phones, wireless access points and a number of other network-connected products. But it provides a limited amount of power. In this tip, David Jacobs investigates the latest...Continue Reading
VPNs: Fundamentals and basics
VPNs are discussed in this introductory tip on the fundamentals of virtual private networks.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
Securing FTP on the Internet
Some companies neglect to secure FTP clients with a solutions such as Secure FTP (SFTP) and a Secure Shell (SSH2) Server. This article explains how to configure and operate an SFTP client (SecureFX) with an SSH2 Server.Continue Reading
Why is the cable supporting my LAN experiencing abnormal attenuation?
Why is the cable supporting my LAN experiencing abnormal attenuation?Continue Reading
Configuring and troubleshooting wireless LAN clients
An understanding of wireless LAN (WLAN) client and WLAN access point communication mechanisms is critical to anyone attempting to initially connect or troubleshoot a WLAN connection. In this tip, Robbie Harrell discusses some of the issues that can ...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
Understanding network traffic flow analysis
Network traffic flow is often compared to highway traffic flow. In this tip, Lindi Horton shows parallels between those two worlds and explains why traffic flow analysis is such an essential piece of knowledge for engineering a network.Continue Reading
Is there really a big difference between cheap, residential-grade wireless APs and expensive, busine
Is there really a big difference between cheap, residential-grade wireless APs and expensive, business-grade wireless APs?Continue Reading
Best practices for network management in the non-profit world
Discover how the Washington, D.C.-based National Parks Conservation Association developed their network management solution to ensure network uptime and availability.Continue Reading
Using Snort, Nessus and Tripwire for network security
Why pay a proprietary vendor a ton of money for a security application you can get for little or no money? In this tip, learn the pros and cons of open source network security tools Snort, Nessus and Tripwire.Continue Reading
Power over Ethernet for network architects
David Jacobs discusses how Power over Ethernet (PoE) is defined by the 802.3af standard, then looks at how PoE can help network architects simplify power distribution and potentially save money.Continue Reading
IP network design, part 4: LAN design
This final section of the IP network design series relates to the issues encountered with campus LAN design. The benefits of Ethernet switching over a traditional hub environment are first explained. The motivation behind the deployment of virtual ...Continue Reading
Certifications that will earn you the most money
Ed Tittel takes a look at the five network certifications that earned the most money in 2005.Continue Reading
IP network design, part 3: Designing the WAN
The wide area network (WAN) is the single biggest contributor to a corporate network's cost of ownership. Therefore, this is the area where the cost-versus-performance tradeoff is most pronounced and most critical. This article explores the various ...Continue Reading
Implementing software restriction policies
This tip explains how you can use software restriction policies to keep your workstations in pristine shape and cut down on help desk calls at the same time.Continue Reading
Router Expert: Initial configuration of a Cisco 1200 802.11g WLAN access point
Our router expert continues his series on building a secure wireless LAN with a Linux base. This article explains how to utilize a single Cisco 1200 series access point to provide access to three different IP network segments using VLANs and ...Continue Reading
LAN connectivity problem: Blame DNS, NIC or firewall?
ITKnowledge Exchange member "BinooDas1234" had connectivity issues with a troublesome LAN, and fellow techies jumped in to help out. But does the answer lie in the DNS configuration, the NIC drivers or elsewhere? Here is a portion of the ...Continue Reading
IP network design, part 2: The IP addressing plan
The IP addressing plan is the foundation upon which a successful logical design is built. Part two of this tip explains how to formulate a scalable IP addressing plan that can support the network as it grows.Continue Reading
IP network design, part 1: Fundamental principles
A competent network design is the foundation upon which all successful network implementations are built. This is the first of four articles that focus on the design of IP-based networks, due to the prevalence of IP as the de-facto standard desktop ...Continue Reading
What is the future of thin access points relative to wireless network security?
What is the future of thin access points relative to wireless network security?Continue Reading
Network asset management software
Network asset management software acts as a watchdog and can help save staff time, downtime, and money -- and thwart security disasters before they happen. David Jacobs explains how it can be of service to your organization in this tip.Continue Reading
OSI: Securing the Stack, Layer 5 -- session hijacking
To help secure your systems against session hijacking, this tip walks you through the steps hackers use to hijack active sessions and take over your network. You'll also learn how to detect and prevent session hijacking attacks, a major security ...Continue Reading
Making sense of Windows routing tables
When routing packets across a network, things do occasionally go wrong. In these situations, it is helpful to be familiar with the Windows routing tables. Routing tables dictate the flow of packets from the machine in question. This tip will show ...Continue Reading
Network security checklist
While 100% security is hardly a possibility, there are several things that you can do to make your network more secure. Learn about them with this network security checklist.Continue Reading
VRFs and routing
Doug Downer continues his series about VPN routing and forwarding instances focused on the task of configuring and verifying a VRF scenario with a requirement for separate customers on a shared device. In this tip, he shows how to configure a method...Continue Reading
Router numbers
Many of the routing protocols implemented in Cisco's IOS require a number to follow the command that enables the routing protocol in question. If you're new to routing, these numbers can be a little confusing, as they mean something different to ...Continue Reading
Wireless LAN security: 802.11i
What is 802.11i, and is it really practical for you to implement in your organization? Robbie Harrell explores how the new wireless standard can improve security -- and reasons why you may want to switch to 802.11i or stick with WPA.Continue Reading
Router Expert: Building VLAN interfaces in Linux and IOS
Segmenting a wireless LAN with VLANs can increase security. Find out from our router expert how to support VLAN interfaces in Linux and Cisco IOS.Continue Reading
Cisco PIX ASDM: How to install
Learn some helpful hints for installing and troubleshooting Cisco's Adaptive Security Device Manager (ASDM) for PIX firewalls in this two-part tip.Continue Reading
Why do we need the MAC address if all Ethernet connections are done via IP address?
Cache poisoning attacks and how to prevent them
Want something scary to think about? A compromise of your name servers could cut you off from the Internet or redirect your customers to a competitor. It could even shunt sensitive electronic mail through an intermediate mail server or reroute your ...Continue Reading
What is difference between a WINS server and a DNS server?
VPN security: Where are the vulnerabilities?
SOX compliance mandates have pushed organizations to deliver end-to-end VPN security. This means that the VPN itself is no longer enough. Robbie Harrell explains how organizations can apply security policies to the VPN in this tip.Continue Reading
How do I open port 177 on my router so that other clients can get a GUI display of my server remotel
Router Expert: Building 802.11Q VLANs
Network segmentation can be a great way to increase security. This article covers segmenting with VLANs and the 802.1Q standard.Continue Reading
Understanding the differences between IDS and IPS
We all know that the Internet is a haven for cyber criminals who use the connectivity to launch an unprecedented number of attacks against enterprise networks. IDS and IPS have been developed to combat these threats, but they are not one in the same...Continue Reading
How do I set up two or more wireless adapters on the same computer to work together?
Keeping it all separate with VRFs
A Virtual Routing and Forwarding (VRF) instance can deliver separation across both a shared infrastructure and shared devices, ultimately simplifying management.Continue Reading
What certification better compliments the MCSE: CCNA or RHCE?
What's the difference between a network assessment and an audit?
The network administrator's guide to forensic first response
The time between discovery of an incident and the handover of digital evidence is critical for the possibility of successful evidence retrieval. Mishandled evidence, whether to be used in court or solely in house, can damage the integrity of the ...Continue Reading
How can I increase bandwidth at my Internet cafe?
Which transmission media are the most secure and the least secure?
Placement of the firewall
In this expert response, Puneet Mehta tells us where the placement of the firewall should be architecturally.Continue Reading
How to protect your network from broadcast and multicast storms
What methods are available to protect a network from broadcast and multicast storms?Continue Reading
Security of each level of the OSI model
What kind of security is associated with each level of the OSI model?Continue Reading
Hardening your router in 9 easy steps
For most enterprise LANs, the router has become one of the most critical security appliances in use. Configured properly, it can keep all but the most determined bad guys out, and if you want, it can even keep the good guys in. But an improperly ...Continue Reading
Router Expert: Standard interface configuration for a WLAN proxy server
Our router expert continues his series on building a secure WLAN with a Linux base. This article covers standard interface configuration of the http proxy server.Continue Reading
Troubleshooting Windows VPN servers
There are several aspects of the Windows remote access server that can create issues when a VPN client connects. This article focuses on some common trouble spots on the server side and offers steps to help pinpoint the problem.Continue Reading
Can I use my wireless router to create a workgroup between desktops?
Can you please explain the following, common Ethernet errors?
What are network collisions and how do they occur? Are they normal?
In a LAN environment, which is better: Token Ring or Ethernet and why?
What is a collision domain? How does replacing a hub with a switch affect collision?
Since DNS uses UDP instead of TCP, if a packet is lost, there is no automatic recovery?
Can I connect two networks, one wired, one wireless, so that I can access the Internet through the s
Wireless LAN deployment and federal regulations
A look at the bare minimum requirements to keep your WLAN compliant with federal regulations.Continue Reading
Secure WLAN best practices and topology
Expert Michael Martin provides a list of wireless security "dos and don'ts" and a sample topology for a secure WLAN.Continue Reading
I need help adding a central MAC address authentication server to our current WLAN.
How can we improve the performance of our LAN?
What does the term "stackable switches" means?
Having two gateways for a network with two routers
IPv6 address types
Part one of a two part series describing IPv6 address formats and how they are used.Continue Reading
How do I block my users from accessing all but a few authorized Web sites?
Seven steps to ensure project success
The Value Manager recently had a project fall well below expectations. He reviewed what happened and came up with seven key steps for managing technical risk and one golden rule.Continue Reading
How do I connect to my LAN from the Internet?