Kevin Dooley

Kevin Dooley

Kevin has 15+ years of experience as a network engineer. He has designed and implemented several of the largest and most sophisticated enterprise data networks in Canada and written several highly regarded books on networking for O’Reilly and Associates, including Designing Large-Scale LANs and Cisco IOS Cookbook. Kevin holds a Ph.D. in theoretical physics and numerous industry certifications.

See more from Kevin Dooley

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Configuration & Troubleshooting

Network Configuration Management: The Benefits & Importance

Configuration management is one of those network management topics people often neglect. Here’s why you shouldn’t.
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Network Management

How to Draw Effective Network Diagrams (Infographic)

Here’s a handy network diagram infographic for creating readable and easy-to-understand documentation.
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Configuration & Troubleshooting

How to Troubleshoot Routing Problems

During equipment setup or failures, issues from design or config errors emerge. Explore troubleshooting tips.
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Configuration & 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, because of a routi
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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 possible. Here are the most effective ways to block a
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Network Management

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 from Auvik.
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Configuration & Troubleshooting

5 Steps to Configure Cisco AnyConnect VPN

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

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.
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Network Management

What is Multicast Networking and How Does It Work?

Multicast networking is based on the simple concept that a single packet can be sent by a server and it will be received by many receivers. Multicast
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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 purpose they serve
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Network Management

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.
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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 to create one
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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 achievable goal.
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Configuration & Troubleshooting

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 devices here.
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Network Management

What is Syslog? A Guide for IT Professionals

Almost every device on a network has a yslog agent you can use to send messages to a central location. Here’s how the network-based logging protocol w
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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.
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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 agencies, and the mere
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Devices

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 changed from t
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Network Management

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.
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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 itself goes down.
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Network Management

How to Adjust TCP Window Size to Improve Network Performance

Seeing poor network performance but with link utilization well below 100%? You might have an issue with your TCP window size. Here’s how to fix it.
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Devices

What to Look for in a Next-Generation Firewall

Considering a next-generation firewall? Here are the most common NGFW features and advice on picking the device that’s relevant to your client needs.
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Devices

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 best practices and more.
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Protocols & Communication

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 configured properly.
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Protocols & Communication

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 here.
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Network Management

The 4 Steps to Safely Removing a Network Device

Unused gear sitting on a network can get very expensive. Here are some general best practices for removing network devices.
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Network Management

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 of a series.
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Network Management

Configuring an Internet Connection for a Cloud-Hosted Environment

Here’s what you need to do to make sure you’re minimizing outages for your cloud-hosted clients. Part 2 of a series.
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Network Management

Here’s What a Network Needs After a Cloud Migration

Dig into the implications of cloud migration and network changes required to make sure a client is set up for cloud success.
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Devices

Migrating a Cisco ASA Firewall Configuration From Old Syntax to New

Cisco made big changes to the configuration syntax on ASA firewalls starting in version 8.3. Here are some real-world pointers.
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Network Management

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

Zero-trust is in the news again with Google’s recent announcement. Here’s what their move means for network security.
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Network Management

How to Configure IPv6 on Cisco Devices

Go beyond the basics of IPv6 and learn how to enable and configure IPv6 on a simple network, including routing and security commands.
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Network Management

What Every Network Admin Should Know About IPv6

IPv6 comes pre-enabled on a lot of network devices—dangerous unless you’re in control. Here’s what you need to know to implement and manage IPv6 well.
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Network Management

An Introduction to Network Authentication Protocols

Centralized authentication improves network manageability and security. Learn about authentication protocols RADIUS, TACACS+, LDAP & Active Directory.
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IT Leadership

How to Explain Highly Technical Ideas to Non-Technical People

Executives really appreciate techies who communicate well. If you value your career, it’s time to get good at it.
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Network Management

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.
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Network Management

Verifying Physical Connectivity

Troubleshooting often means swapping elements. Aim to pinpoint issues, minimizing the number of swaps.
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Network Management

Configuring SSH on a Cisco Device

SSH is like Telnet, but encrypted. Configure it in 6 simple steps and don’t use SSH version 1.

What’s your shadow IT risk factor?

Find out in this free guide and exercise kit.
book cover - The Modern Professional's Guide to Shadow IT
You will learn:
  • The impact shadow IT has on an organization
  • How to evaluate tools
  • Tips on security
  • A quiz to help you determine the severity of shadow IT in your org
  • Solutions to solve these problems