1031 exchange and debts calculation when selling rental

There's one thing I still don't get it with 1031 Exchange. Lets say your equity in the rental property is 25%. So remaining mortgage debt is 75%.

If I do 1031, I need to reinvest the whole 100% from the transaction. Then how do I get the money to finish the 1031 transactions? Does it mean that I need to make another mortgage for the new 1031 property? 

Also, does the same thing applied to 1031 DST as well?