Articles written by Kevin Dooley

Troubleshooting

Finding & Fixing Asymmetric Routing Issues

The workstation at the bottom sends a packet to the server along the green path, and it goes through the firewall on the left. But,…

Cybersecurity

Defending Your Network Infrastructure Against Attack

Since perfect network security is impossible, your goal is to cover as many of the risk areas as you can with the budget you have. In…

Network topology & mapping

What Is a Network Diagram?

What is a network diagram and why is it important for your business? Learn more about the importance and purpose of a network diagram…

How to Draw Network Diagrams

Good network diagrams aren't hard to make, yet they're distressingly rare. Even network engineers with years of experience often make…

5 Steps to Configure Cisco AnyConnect VPN

Follow these 5 simple steps to configure Cisco AnyConnect VPN on ASA firewalls for your network.

Network management

What are Network Address Translation and Port Address Translation?

NAT—network address translation—is an important tool for both conserving IP addresses and enhancing security. Here's how it works.

Cybersecurity

The Pros and Cons of VPN Split Tunneling

Should you use VPN split tunneling? Here's what you need to know to decide.

Network configuration

Configuring and Troubleshooting Multicast Protocols

There are two important protocols required to get your network to forward multicast packets. Here's how to configure & troubleshoot them.

Network management

What Is Multicast Networking and How Does It Work?

Multicast networking is based on the concept that a single packet can be sent by a server & it will be received by many receivers. Here's…

Network management

Special IP Address Ranges and When to Use Them

There are several special IP address ranges that have specific purposes. Network engineer Kevin Dooley explains what they are & the…

Subnetting: What it is and how it Works

You don't need that subnet calculator! Not when you have this handy guide to subnetting using both mask and CIDR notation.

Cybersecurity

Implementing a Bring Your Own Device Policy in Your Organization

A bring your own device policy is more important than ever since users can bring unsecured personal devices into your office. Here's how…

Cybersecurity

What is a zero-trust network?

The cybersecurity landscape has changed a lot thanks to the increase in cloud-based services, and zero-trust is now an extremely…

Network configuration

How to Configure Syslog on a Cisco Device

Every modern network device has at least some syslog capabilities. Learn all you need to know about how to configure syslog on Cisco…

Network monitoring

What Is Syslog and How Does It Work?

Almost every device on a network has a syslog agent you can use to send messages to a central location. Here's how the network-based…

Network management

An Introduction to Web Proxies

Web proxies intercept traffic from your systems as they move to others, analyze the packets, and send the data along.

Network management

Not All Hacks Are the Same, Plan Your Network Defenses Accordingly

There’s a vast difference between the incredibly sophisticated long-term attacks against high-profile companies and government…

3 Switch Features You Should Never Change

In a handful of recent incidents, I helped clients troubleshoot network problems. The errors turned out to be switch features that were…

Network Time Synchronization: Why and How It Works

One of the keys to effective network management is syncing clocks on all network devices. There are really two ways to do it.

Network Redundancy and Why It Matters

Complexity is an enemy to reliability. The more complex something is, the harder it is to understand, the greater the chance of human…

Network configuration

Network Configuration Management: The Benefits & Importance

Configuration management is one of those network management topics people often neglect. It’s not very exciting—but it’s incredibly…

Network management

The New DR: What To Do When the Internet Is Down

With the move to cloud, disaster recovery has become a special challenge. You now have to worry about what you’ll do if the Internet…

How to Adjust TCP Window Size to Improve Network Performance

Are you seeing poor network performance but with link utilization well below 100%? You might have an issue with your TCP window size.…

Network management

What to Look for in a Next-Generation Firewall

Considering a next-generation firewall? To help you understand the huge array of available options, engineer Kevin Dooley describes the…

Network management

Network Basics: What Is Link Aggregation & How Does It Work?

Link aggregation is a way of bundling a bunch of individual Ethernet links together so they act like a single logical link. Learn more on…

Firewalls

Cisco ASA ACL Best Practices and Examples

ACL on a Cisco ASA firewall looks simple, but becomes unwieldy if not organized and managed. Learn more about Cisco ASA ACL best…

6 Common Spanning Tree Mistakes and How to Avoid Them

Spanning tree is a Good Thing. It saves you from loops, which will completely shut down your client's network. But it has to be…

Network management

Network Documentation Best Practices: What to Create & Why

Everybody agrees network documentation is extremely important, but there tends not to be a lot of agreement on what that documentation…

The 4 Steps to Safely Removing a Network Device

Unused gear sitting on a network can get very expensive. Get it off there! Here are some general best practices for removing network…

Managing User Access & Authentication in a Cloud-Hosted Environment

One of the things that becomes more important in a cloud-based application environment is managing user access and authentication. Part 3…

Configuring an Internet Connection for a Cloud-Hosted Environment

When a company’s application infrastructure moves to the cloud, a reliable Internet connection becomes mandatory. Unfortunately, the…

Here’s What a Network Needs After a Cloud Migration

In this three-part series, we dig into the implications of a cloud migration and outline some of the network changes that are required to…

Migrating a Cisco ASA Firewall Configuration From Old Syntax to New

Cisco made huge changes to the configuration syntax on ASA firewalls starting in version 8.3. Here are some real-world pointers for…

Network topology & mapping

How to Draw Effective Network Diagrams (Infographic)

Auvik lays out everything you need to know about drawing and creating network diagrams. Check out this infographic for help on how to…

Google, Zero-Trust Networks, and the Future of Security

Back in January, I blogged about zero-trust network architecture as an emerging trend. Zero-trust is now in the news again with Google's…

How to Configure IPv6 on Cisco Devices

In this followup to What Every Network Admin Should Know About IPv6, network engineer Kevin Dooley shows you how to enable and configure…

What Every Network Admin Should Know About IPv6

IPv6 comes pre-enabled on a lot of network devices — that’s dangerous unless you’re in control. Here’s what you need to know to…

An Introduction to Network Authentication Protocols

Centralized authentication improves the manageability & security of your network. In this article, network engineer Kevin Dooley…

8 Networking Trends to Watch in 2015

What networking trends will we see come to life in 2015? Think security, speed, and cloud.

How to Explain Highly Technical Ideas to Non-Technical People

Executives really appreciate techies who communicate well. It's a rare skill and it translates into promotions and bigger paychecks…

Stop! Are You About to Make One of These Network Management Mistakes?

Network pro Kevin Dooley shares the stories of four painful network management mistakes -- and tips on how you can avoid the same goofs.

How to Troubleshoot Routing Problems

Routing problems tend to emerge when you're first setting up a new piece of network equipment, and when something has failed. Usually…

Verifying Physical Connectivity

Many physical troubleshooting exercises come down to the process of swapping out elements until the problem goes away. The key is to…

Configuring SSH on a Cisco Device

SSH (Secure Shell) is a command line interactive interface, similar to Telnet, but encrypted. Learn how to configure it in 6 simple steps…