Hewitt and N'Daw make their bows in Town shirt
Trialist Bilel Mohsni also featured for the first time for Town, playing 90 minutes in the centre of defence.
N'Daw came close to opening the scoring with a long range effort that landed on the roof of the net before Blues did get ahead just before the break, Mohsni flicked on a Hewitt throw with a touch from a defender taking the ball in.
Arran Lee-Barrett was called into action at the start of the second-half with a fine low save to stop the visitors drawing level.
Half-time substitute, Kyle Hammond, made an instant impact after replacing Hewitt at right-back. The teenager latching onto Nathan Ellington's cross to the back post with a strong header to extend Town’s lead.
Mohsni got himself on the scoresheet with Town’s third, his shot from distance evading Elliott Parish in the Cardiff goal.
Five minutes later Blues were four up, this time with left-back David October making a powerful run into the left side of the box and shooting across Parish into the far corner.
Town made it five with substitute Mark Timlin scoring with six minutes left and Jack Marriott completed the scoring after a mistake in the Bluebirds’ defence.