Pressure continued and Jon Walters opened the scoring with a curling left footer from 20 yards that gave keeper Carl Ikeme no chance as it found the top corner.
Smith crossed to set up Walters for another chance, but he missed the target, firing too high. And then Ferguson had a close range shot deflected for a corner.
Walters blazed another drive over the cross bar and missed a sitter when Dean Bennett put him though, putting his shot a foot wide of the far post.
Meanwhile County were pinned back in defence and seldom crossed the half way line, although Ashley Williams was unlucky with a shot that Danny Williams cleared off the line following a Matty Hamshaw corner.
Wrexham went further in front early in the second half. Youngster Mark Jones beating Ikeme from the edge of the area from Alex Smith's cross.
Again when Jones went through on the left, and Smith crossed, Ferguson's diving header went wide.
Jones was always in the game and hit his second goal with a low strike from 25 yards out that went inside the left post before the keeper had time to see it on it's way through a crowded defence.
Stockport had completely lost their way and when Malcolm had a half chance set up by Hamshaw, he missed the target by yards.
County made a triple substitution, taking the risk of being another man short if they had an injury, but the chances made little difference.
Hamshaw missed twice with shots over the top and, when he drove a free-kick into the area, substitute Tes Bramble hit the post.