Doesn't DR anymore, not from 5.0 and further, as you can see here, because Ring of Frost was an instant cast(and you couldn't see where it was being casted), so you could get 8 sec CCed instantly into another ~~3/5 seconds frmo Deep Freeze, which was the reason.
Now from 5.0 and further, you can see where Ring of Frost is being casted and it is not an instant cast anymore(not without PoM), thus removing the DR.
To complement my answer: