7*24 or 5*8 ? Email or telephone or remote support?
definitly mon-fri, but the support crew is located across the globe, and depending on which Dynatrace product you need support for - this will vary (due to timezones..etc).
Also depending on what kind of issue you need assistance with. If its an actual bug (I’ve found several) - fixes can go from as short as a couple of days to several months. (my personal experience with appmon, dcrum and synthetic).
I’ve had many supporters i could simply call up or Skype/lync/webex with, but naturally they have to triage the ticket first.
Here you can find more up-to-date answer:
Dynatrace Support Policy
Of course, you can always count on the Dynatrace Community! 
It’s a thriving Community, and a lot of people are here even out of business hours 
@573594233 Exactly I support what @AntonioSousa writes - if you can’t find something in the documents or the university, you always have a whole community, which just for this product works in an insanely positive way 