I would like to stress that the gravity of this situation is that for rack or standalone server like R620 After you re-connect the power cables DRAC access is not instant.
Booting DRAC is a long process that last probably a couple of minutes.
Random hangings of i DRAC7 on R620 when you can't connect to it remotely either via ssh or HTTPS proved to be very consistent if you access DRAC with large intervals.
What Dell (unlike HP and CISCO) did right is that on rack servers like R620 and R720 it provides a button with the letter i on it (i-button) to reset DRAC on the front panel of the server.
Blades are not affected as DRAC in blades can be rebooted from the enclosure controller.
This is essentially the same blunder as as HP SNAFU with i LO 3 -- often So you have the situation, when the last time you use DRAC it was OK, then the next time, in a month or two you can't connect.
From Google search on the topic it is clear that this problem exists since the release of DRAC7 at the beginning of 2013.So it you have a lot of identical or similar Dell servers (for example Dell enclosure with 165 blades) it has additional value as automation tool for routine operations In case you don't have personnel on a remote site this is a disaster and big SNAFU for DELL.In the rat race for additional functionality they forgot the primary purpose of the DRAC -- to be reliable KVM -- and the main criteria of its usefulness -- reliability.Recent version, such as 1.57.57 are better but still hands during regular operations, for example if you perform some operations with v Flash. also they require recent version of Lifecycle controller and BIOS to the installed too.God forbid you to update just DRAC firmware, you might completely hose the box and DRAC even after shutting server down and removing cable will remain un-operational, or operational for a minute or two, after which it hangs.But, in a way, DRAC went one step further that HP is this "spontaneous hanging" problem: it hangs just after certain amount time of being up. Brilliant automation of locking sysadmin out of the remote server !