Tuning Large Windows DHCP Servers

I’ve been involved in setting up some very large Windows DHCP deployments during my time working as a Consultant at Long View Systems. Along the way I’ve found some interesting challenges and caveats of using Windows DHCP, especially so anytime your working with DHCP enabled dynamic DNS updates. I wanted to have a quick post about this for my own reference and hopefully might come in handy for others as well.

  • DHCP Failover Scopes
  • Administration Overhead
  • DhcpLogFilesMaxSize
  • DynamicDNSQueueLength
  • DnsRegistrationMaxRetries

DHCP Failover Scopes

I’ve covered this topic extensively in my Windows Server 2012 R2 – DHCP High Availability / Fail-over Setup Guide series. Basically, if you are deploying Windows DHCP on a 2012+ server then you should be using DHCP Failover (not to be confused with split-scope or ms-clustering).

Administration Overhead

If you’re working with more than 100 scopes using only the default DHCP MMC-snap in’s, you’re gonna have a bad time.

Almost 1,000 DHCP scopes, 150k+ IP addresses

Performing administration tasks in the console with a large number of scopes becomes very repetitive and time consuming as each task normally requires many clicks. Making mass-changes is also very difficult or next to impossible. You may find yourself becoming familiar with Powershell scripting to resolve this problem. The DHCP Server Cmdlets in Windows PowerShell are very easy to use and Microsoft has great documentation on this. I found myself making Powershell scripts to make mass-changes much easier and less vulnerable to human error due to the very repetitive nature of the default GUI. Continue reading…

Migration from Cisco 1000v to VMware Virtual Distributed Switch (Part 2)

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This is part 2 of a series. Click here to see Part 1. I apologise for taking so long to get Part 2 posted. Sometimes I just don’t have the time or effort I would like to have with the blog.

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This portion of the guide focuses on the second half of the VSS to VDS migrations. We needed to move the VMs to a VSS so that you can migrate both VMs and hosts to the new vCenter cleanly. Then we will be moving the VMs back to a VDS from their VSS configuration.

Keep in mind this migration is being done LIVE with production virtual machines running on the hosts. Obviously, this must be executed carefully or you will have a lot of explaining to do. Do not make these changes without understanding the full impact to your environment. Continue reading…

Firewall Swap & Windows Telemetry Data

I recently switched over from Sophos UTM to Untangle NG for my personal use firewall at home. During the process I basically had to rebuild all of my firewall rules and general network policy configurations. This allowed to me “start fresh” as my previous configuration had gotten quite bloated and complicated over time.

It’s clear that Microsoft has no intentions of telling us what exactly is sent in this telemetry data, how long it’s stored, and why when it’s disabled it continues to send data. Not to mention which obvious third parties have access to the data. For this reason, part of the new network policies I wanted to include was blocking telemetry data from getting sent back to the Microsoft mother-ship. Continue reading…

WHMCS – Is the promo applied or not?

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WHMCS is one of the most popular billing systems for web hosting companies. Despite this fact there are many small caveats and grudges you will find with the WHMCS platform.

For example, when a customer is passed to an order page using a link with a promotional code or with an existing promo code applied the order summary does not show the discounted total. The discounted total is only shown on the checkout page. How stupid? This simple mistake by WHMCS’s developers can not only increase customer cart abandonment rates but also confuse the customer whether the discount is applied or not. Put simply, it grinds my gears as well. Continue reading…

My first dedicated server, back in 2005

This is a short post about my first ever dedicated server… back in 2005. I seldom forget exactly how long I’ve been involved in the web industry. I took a moment to reflect back in time. Using the WayBackMachine I was able to find the company’s page and details. I rented my first dedicated server from a company called AngelNetworkz. This image below is exactly how I remember their website and page looking.

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Continue reading…

Virtual Firewall and Networking – Planning Guide

This is a planning guide on how to create a robust, redundant, virtual network for your home-lab environment including a virtual firewall. This requires a lot of existing hardware and expertise. This is not recommended the faint of heart and will challenge you. Using a physical firewall is the easy choice.

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I have structured this guide around how I have my own network configured for the vSkilled home lab. I have been running in this configuration for literally years without incident. You should first weigh the pros and cons for your own environment and then decide if this design is the right choice for YOU. Just because it works for me, does not mean it will work for you. There are many mixed opinions between running your firewall physically or virtually. Neither is right or wrong. That really depends entirely on your skill level and the equipment you have available. You should decide on a network topology which you are most comfortable troubleshooting and fixing when it breaks.

Continue reading…