Stunning goals from Jai Reason and Courtney Pitt rounded off an emphatic 4-0 victory for Cambridge as Ilkeston were sent packing at Abbey Stadium.
Chris Holroyd scored his 15th goal of the season before Reason's touch of class and a superb free-kick from Pitt made United's place in the second round safe.
And there was still time for Cambridge substitute Adam Marriott to add a fourth on his home debut as they outclassed their Blue Square North opposition.
Holroyd proved exactly why he tops the Blue Square Premier goalscoring charts, pouncing on the loose ball to slot past Robins goalkeeper Dan Lowson after five minutes.
The visitors did have chances of their own in the first half but Amari Morgan-Smith just failed to reach a poor backpass from Wayne Hatswell after 15 minutes.
Cambridge defender Brian Saah had an excellent chance to double the hosts' advantage after 28 minutes but he headed high and wide after a fine cross from Rory McAuley.
Robbie Willmott reached the by-line and pulled back for midfield maestro Reason and he smashed home from 20 yards in the 64th minute.
And nine minutes later Pitt, once on the books of Premier League side Portsmouth, struck an unstoppable free-kick inside the far post before Marriott completed the rout with a well-taken 20-yard drive late on.