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.
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?
Can I have two Internet connections -- one the VPN and one not?
Is it possible to have two connections to the internet running simultaneously, one running a VPN and one not? If so, how do you determine which connection a given user session will use? I am running XP. Continue Reading
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Establishing communication between two networks via switches
I have two 3Com layer 3 switches (4924) connecting to two separate networks in a building. How do I configure these switches so that the communication can be established between the two networks?
These two networks are on the first and second ... Continue Reading
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
User acceptance test plan for 1000-branch WAN
My vendor has asked me to prepare a user acceptance test plan for a WAN of 1000 branches, which have leased line and ISDN connectivity. What are the specific parameters I should look for at each branch connection? The vendor has just specified ping ...Continue Reading
What are intusion detection and intrusion prevention and how do they work?
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What are the system requirements for connecting elevators in a high-rise building via a wireless net
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's the difference between a network assessment and an audit?
What certification better compliments the MCSE: CCNA or RHCE?
How do I set up two or more wireless adapters on the same computer to work together?
How do you get five switches to talk without using a routing protocol?
I want to add five catalyst 3550 IOS switches to a single 4506 Cisco router so that each switch will have its own subnet. 192.168.10.0, 192.168.11.0, etc.. how do you get all five switches to talk without using an routing protocol like OSPF or RIP ...Continue Reading
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
Why can I connect to or ping some computers via my Cisco VPN connection but not others?
Why can I connect to or ping some computers via my Cisco VPN connection but not others? I use Remote Desktop Connection to connect to various computers on our corporate network (Windows XP PRO on all machines and each one has been allowed to receive...Continue Reading
Practical configurations: Extending the OSPF network
Doug Downer continues his series on network configuration with a focus on adding external prefixes such as static routes into your newly created OSPF network and also how to manipulate these routes as they travel across each layer.Continue Reading
RIP security
If you're stuck with RIP, it doesn't mean you can't improve your system's security. Assuming you have a Cisco router and version of IOS released this century, this tip will explain the few easy commands required to prevent people from sending you ...Continue Reading
How can I increase bandwidth at my Internet cafe?
Placement of the firewall
In this expert response, Puneet Mehta tells us where the placement of the firewall should be architecturally.Continue Reading
How do I remove Trojan viruses that have infected my network?
Which transmission media are the most secure and the least secure?
Where are the best networking jobs for a CCNA?
Practical Configurations, Part 3
This section explains how to configure your distribution and core devices to route traffic to its proper destination and includes some simple commands to help validate your configuration.Continue Reading
Security risks of firewalls and VPNs
What are the key security risks and considerations to adopt firewall/VPN technology?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
Advice on making the transition from network engineering to network security
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
EventCombMT: Search for specific events on Windows event logs
If you've ever wanted to do quick and dirty searches on event logs for multiple Windows machines, contributor Serdar Yegulalp says don't go without: EventCombMT. Find out how to use it in this tip.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 the advantages and disadvantages for pure IP over IP-enabled solutions?
What is a network sniffer?
In a LAN environment, which is better: Token Ring or Ethernet and why?
What are network collisions and how do they occur? Are they normal?
IPv6 renumbering
Renumbering IPv4 networks has always been a difficult job for network administrators. With IPv6 it becomes easier. The protocol's ability to support multiple addresses on a host enables a gradual conversion.Continue Reading
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
What Ping doesn't tell you
Ping distinguishes certain states of network functionality that are the cornerstones of everyday network troubleshooting. Learn how to gain greater insight into your network.Continue Reading
How do I configure a switch port to full-duplex and another to auto-sensed from a 24-port Cisco 2950
Wireless LAN deployment and federal regulations
A look at the bare minimum requirements to keep your WLAN compliant with federal regulations.Continue Reading
What's needed to wirelessly connect two offices 100 feet apart?
Cannot connect to Internet or local network while on the VPN
Top five tips for improving network performance
Here are five things you can try to improve network performance without buying new hardware.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
Can you explain the importance of upgrades and patches and what the differences between the two are?
I need help adding a central MAC address authentication server to our current WLAN.
Interconnecting hubs and switches
Connecting hubs and switches in your network would seem to be a fairly common and basic procedure, but there are a few things to look out for.Continue Reading
Routing protocol basics, part 1
A detailed look at the characteristics of IGP routing protocols RIP and IGRP/EIGRP.Continue Reading
How long do I have to finish the CCNP exams before my CCNA runs out?
What does the term "stackable switches" means?
How can we improve the performance of our LAN?
Can you tell me about wireless LAN QoS and what are the pros and cons of implementing this?
Can SACK and FACK help to minimize packet loss on my WAN?
How to set up two VLANs with secure Internet access through one router
How can I set up two VLANs with Internet access provided for both via one router, but maintain security between the two (i.e. so nobody from the first VLAN can gain access to the second VLAN and vice versa)?Continue Reading
What are the differences between physical and logical addressing?
Transition IPv4 to IPv6: How address formats are used to convert IPv4
What the longer IPv6 addresses can do and how to ease the transition from IPv4.Continue Reading
PIM RP configuration methods
How to configure Auto-RP, a method of setting the RP, or rendezvous point, on a PIM-SM network.Continue Reading
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
Is there a difference between Wi-Fi and WiMax?
How do I block my users from accessing all but a few authorized Web sites?
How can I fix a corrupt DHCP?
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
Configuring main and backup leased lines
How can I access my Cisco router from the Internet?
Authentication weaknesses
This tip focuses on hardening network access against brute-force attacks.Continue Reading
Is VTP a proprietary protocol of Cisco?
How do I connect to my LAN from the Internet?
What about using SSL VPN with e-mail clients?
Over the SSL VPN can you reconfigure your email client to send traffic over SSL to the e-mail server? Find out in the Q&A with expert Lisa Phifer.Continue Reading
The Multi Router Traffic Grapher
A short review of a free network traffic monitoring tool called the Multi Router Traffic Grapher.Continue Reading
Router Expert: Filtering with MAC addresses
This month our router expert discuss some strategies for controlling host network access using MAC address filtering.Continue Reading
Network management and troubleshooting
Networks administrators guide to management and troubleshooting.Continue Reading
Focus Windows port scanning with the netscan command
How to use the netscan command to focus Windows port scanning.Continue Reading
What are the basic features of CIDR and what are its advantages and disadvantages compared to IPv6?
What are advantages to IPV6 regarding mobility and wireless? Are there any?
Multicast trees
How multicast propogates in a tree style and what to expect from source trees and shared trees.Continue Reading
Can I connect two computers through Ethernet on a WAN?
Can I connect two computers through Ethernet on a WAN?Continue Reading
What costs I can expect when designing A LAN? How can I keep costs to a minimum?
Can you please explain to me how satellite ATM networks work?
Why is full duplex important to VoiP applications, more so than half duplex?
Redundant security
With trusted algorithms being cracked left and right, here's a way to implement layered security controls.Continue Reading
How do you interpret a bandwidth utilization graph?
What is a LAN and how does it work?
What can you tell me about traffic and the scanning process?
What is your opinion of Fortinet's FortiGate Firewall?
Is Fortinet's FortiGate Firewall product right for your organization? Our expert discusses the product's features and capabilities.Continue Reading
Why Do You Need a Firewall? from 'Firewalls For Dummies'
Why Do You Need a Firewall? Chapter 1 of "Firewalls For Dummies" provides an excellent overview of what a firewall is, what it does and how it works.Continue Reading
Public vs. private networks
ITKnowledge Exchange member "rpvish" had a question about how to ping internal and external networks, and fellow techies helped out. Here is a portion of the conversation.Continue Reading
Multicast group membership
A look at the mechanisms and protocols used to join multicast streams.Continue Reading
I need a very basic VPN solution to connect two offices to allow two servers to talk to one another.
Why can't I ping the server from a machine on a different network?
Why can't I access my folders on the server through the VPN?
Can one use VPN over a peer-to-peer network within a home?
How do I represent expired certs on my resume?