Articles written by Kevin Dooley

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…

An Introduction to Subnetting

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

[image] Implementing a Bring Your Own Device Policy In Your Organization

Network management

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…

[image] Why a Zero-Trust Network Is More Desirable—and Achievable—Than Ever

Cybersecurity

Why a Zero-Trust Network Is More Desirable—and Achievable—Than Ever

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

[image] How to Configure Syslog on a Cisco Device

Network configuration

How to Configure Syslog on a Cisco Device

Essentially every modern network device has at least some syslog capabilities. Here's how to configure syslog on Cisco devices.

[image] What Is Syslog and How Does It Work?

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.

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

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…

The Why and How of Syncing Clocks on Network Devices

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

Simple Network Redundancy: Creating Maximum Availability With Minimum Complexity

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

The Benefits of Great Network Configuration Management

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

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

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.…

[image] Network Basics: An Introduction to SD-WANs

Network management

Network Basics: An Introduction to SD-WANs

The basic idea of an SD-WAN is to reduce MPLS or other fixed internal WAN circuit costs by shunting some or all of your traffic over…

[image] What to Look for in a Next-Generation Firewall

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…

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

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.

Implementing ACLs on a Cisco ASA Firewall

The first line of defense in a network is the access control list (ACL) on the edge firewall. The challenge is that while ACLs can be…

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…

[image] Network Documentation Best Practices: What to Create & Why

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…

Defending Network Infrastructure Against Attack – Part 2

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…

Defending Network Infrastructure Against Attack – Part 1

It’s impossible to create perfect network defenses. But it's not terribly hard or expensive to mount an effective defense. Let’s…

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…

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 Authentication Protocols

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

The Secrets to Drawing Effective Network Diagrams

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

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…

Network management

Out-of-Band Management

Out-of-band management provides a way to log into your network devices without going through the same network through which the data…

Configuring Syslog and SNMP on a Cisco Device

There are two common ways to get management information about your network devices to a central server: syslog and SNMP. Both are fairly…

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…