For most of our users that simply want to know if their website experiences an issue, monitoring by website is the ideal approach. Below, we'll do our best to explain the differences.
Monitoring by Website
When we monitor by website, our platform performs a lookup of your domain name. It looks for what's known as an A or AAAA record. That record tells our platform where your website is located (what IP address is associated with your website). We then connect to your website using an HTTP client, log the HTTP status code, and log the amount of time it took for the server hosting your website to respond.
This allows us to generate latency graphs and provide information on outages that might help you (or your hosting provider) track issues that are happening.
When we monitor by website, we can also watch your DNS records for major changes and watch your SSL certificate to let you know when it will expire and if it's experiencing any issues.
We do not recommend enabling A/AAAA record monitoring for websites that use services such as CloudFlare as they can frequently change your A records, which will lead to constant change notifications.
Monitoring by IP Address
More advanced users that operate their own servers will end up using this option. When we monitor by IP address, we're performing a ping test (ICMP Echo), logging the response time, and marking online/offline based on the connection as a whole.
While not yet available at the time of writing this article, we will also be introducing individual service monitoring shortly that will allow hosts to have common ports monitored (IMAP, POP3, SMTP, SSH, MySQL, etc...)