What is a Feeler Connection? When is it used?

[Bitcoin]

What is a Feeler Connection? When is it used?

The bitcoin client hard codes a limit of 8 outbound connections. Your node will try to always maintain these 8 outbound connections with reliable peers as a defense against network attacks. But there is an ephemeral 9th outbound connection called a feeler connection. What is the purpose of a feeler connection and how does it work?

Source: What is a Feeler Connection? When is it used?