The ramblings of a computer geek
Tristan Self 
Multicast is a networking method used to efficiently transmit data to multiple recipients simultaneously. Unlike unicast (one-to-one) and broadcast (one-to-all) communication, multicast is a one-to-many or many-to-many method where data is sent only to devices that are interested in receiving it, rather than to all devices on a network. In multicast, devices that want to … Read more
You can use EC2 Instance Session Manager to give you direct console access without the need for an SSH connection direct to the instance (which can cause some security issues), instead you can get the same kind of access via the AWS CLI. These instructions assume you have an EC2 instance already setup and working … Read more
Elastic IP Addresses (EIP) are great as they provide you with a static IP address which you can use for an endpoint to your application, but when you are automating things with Terraform, you don’t want it to be continually re-created or that IP address will change, and if you have DNS records pointing at … Read more
It used to be easy to flush the cache, but recent changes to the DNS Client on Microsoft Windows 10 (and 11) have made this more difficult, you used to be able to run an “ipconfig /flushdns” or failing that restart the “DNS Client” service, but these don’t appear to work any longer. However you … Read more
The Nissan LEAF provides limited information via the normal information systems in the car as to what is going on with the drive train and more specifically the battery. However, there is an phone app that is available for Apple IOS and Android called “LEAFSpy Pro” that can provide you with detailed information; something that … Read more
We use SMTP on our Exchange Servers to provide authenticated SMTP email service for those who are using email clients which require SMTP to send email. We had an issue that following a certificate expiry that any SMTP connections to the server (that were attempting to use STARTTLS) would fail. For example: The issue was … Read more
VMware gives the capability to “snapshot” a powered on or powered off virtual machine, preserving its state at a particular point in time. Although this is a very useful feature, is it not intended as a long term backup, archive or for example a pre-upgrade/change state backup. A snapshot allows an administrator to create a … Read more
The Palo Alto Firewall GUI is really slick, but sometimes its handy to create using the CLI, perhaps if you have a large number of changes that need to be made at once. Within this example, we’ll create a zone, then an Interface (on an Aggregate Interface), give it an IP address, apply a management … Read more
We had an issue where a recent Windows update broke the Exchange Server, luckily booting into safe mode and removing it resolved the issue, however although the databases mounted okay, there was one that did not. We attempted the typical ESEUTIL steps because it was reporting “dirty shutdown”, and got the database back to a … Read more
Multicast is a networking method used to efficiently transmit data to multiple recipients simultaneously. Unlike unicast (one-to-one) and broadcast (one-to-all) communication, multicast is a one-to-many or many-to-many method where data is sent only to devices that are interested in receiving it, rather than to all devices on a network. In multicast, devices that want to … Read more