Dedicated Internet Access

Dedicated Internet Access (DIA) is a specified amount of bandwidth that has been carved out from your ISP and dedicated for your use.

What you need to know.

In the case of critical business uptime and reliability, the method with the most reliability would be using a “dedicated” line.

"Best Effort" internet access is a "maximum" amount of bandwidth you can hope for.  For example, if you contract for 10mb/s that is the most you will have, not the least.  If you contract for 10mb/s with a DIA, that is the minimum you will get.