I tried using zabbix earlier, however, I was much more confident with Nagios just because of its vast community-based plugins, and active community support, even you can have Nagios Core Paid Support by paying approximately 2200 U$/year.

Some of my known Nagios Community Members have started deploying check mk product but still I stick to Nagios Core.

I previously used SolarWinds. I switched to Nagios Core because it's a unique solution, it's easy to install and troubleshoot, and there's a lot of documentation on the internet.

We were working with ELK. Due to costing we switched to Nagios Core because it is free for the alerting feature. 

I used Pandora about seven years ago, so I can only speak about the capabilities of the solution as it existed at the time. Pandora was excellent, but the documentation was too complicated.

I have worked with Centreon in my organization as well.

I had used this solution before and there wasn't anything in place here that was any good, so it was a no-brainer for me.

My most important criteria when selecting a vendor are 

• flexibility
• supportability
• scalability.

I have not used another solution previously.

Nagios is the first one.

We did not previously use a different solution. Nagios was the first solution that we started using 10 years ago.

I am using SCOM in parallel to Nagios Core, it's a monitoring solution by Microsoft. However, I prefer Nagios Core.

I have used Zabix and Big Brother, but neither was as workable as Nagios.

I tried Zabbix and OpenNMP but I didn't like them. I use Cacti and SmokePing for detailed graphics.

The outgoing system ws Network Eagle which was good at monitoring but not very good at presenting its results. Nagios was certainly a step up as we had previously needed to use a Visual Basic add on to display results which was limited to little more than a ping test display.

We did previously use a different solution. We still use it. It continues to monitor our network. We have a new CTO that is looking to make changes. We're evaluating more economical options.

No, this is the first one that we started using. There was nothing that we have to complain about here from the past experience.

This is our first infrastructure monitoring tool.

I never used a different solution because this current position is my first. Nagios was already set up before I joined the company. Nagios was already good enough for us so we didn't allocate time to research other products.

This was our first monitoring solution. We were looking for a way to monitor IT structure as some years ago we began deploying a few servers and switches. Over the years, computers have spread everywhere into our offices and factory, so we needed a way to check for systems/network availability 24x7. Nagios Core was a good solution to start with.

I started with this product.

Tried many other similar products all demo versions hence did not take to production

I used Centreon/Nagios for eight years before I chose Nagios with the Adagios interface to simplify day-to-day configuration.

Nagios was our first solution. At the time, we read that Nagios was the industry standard solution, so we chose it.

We use Cisco ASA and MySQL devices alongside Nagios as our network infrastructure needs expanding and required more serious hardware solutions.