IPMI offers a way to remotely power-cycle a machine, as well as to have remote console viewable to see the machine boot from BIOS.You can change BIOS settings, reboot the nodes, and watch them boot up and see the console screen without ever seeing the machine.But this capability are valuable only is the device that provides those services is 100% reliable.As such it is a backdoor into server and connection to DRAC should be on a separate segment which needs to be controlled by a firewall.Number of security holes in DRAC is unknown but should be assumed as considerable as this is complex and versatile product that is using Linux as the base of imbedded OS.The DRAC is a separate computer with a different chipset, RISK CPU and motherboard that is connected to the server main board but has its own network interface.It runs custom version of Linux so there are plenty of vulnerabilities to exploit by three letter agencies like NSA.For example Lifecycle Controller 2.0 technology enable to update BIOS via DRAC.
It provides more useful capabilities for a remote sysadmin and makes Dell server preferable to competitors in such situations.
In other words it is closer to the ideal solution which allow to manage servers as if sysadmin is physically near the server.
DRAC supports multiple users, each with unique password.
Since IPMI 2.0 has become the current standard hardware vendors now incorporate hardware for remote management on most servers.
It exists is three versions: Basic Management, Express, and Enterprise.With Drac7 Dell offers a much deeper, more powerful solution that iether HP or CISCO.