I86bilinuxl3adventerprisek9m21573may2018bin -

To understand what this file does, you have to break down the Cisco naming convention used in the binary:

Below is a breakdown of what this file is, how it’s used, and why it remains a staple for network engineers. i86bilinuxl3adventerprisek9m21573may2018bin

Understanding i86bilinuxl3adventerprisek9m21573may2018bin: The Backbone of Virtual Labs To understand what this file does, you have

Because it is an "Advanced Enterprise" image, it supports almost everything needed for CCNP and CCIE labs, including MPLS, IPv6, and advanced IP Services. Deployment in Virtual Labs To understand what this file does

You won't find this file on a standard Cisco router. Instead, it is used in: