Presumptive Democratic nominee Hillary Clinton took a jab at Donald Trump Wednesday by saying she didn't know of any wall that would "keep the Internet out."

Trump has promised to build a southern border wall with Mexico. There are, of course, firewalls and other cyber-security measures that can be employed in the fight against terrorism.

Clinton, speaking in Hampton, Virginia, about national security, said Trump was temperamentally unfit to be president, pointing to his proposed Muslim ban. Speaking about Omar Mateen, who killed 49 people on Sunday in Orlando, she noted he was born in New York.

"[Mateen] was born in Queens, New York, only miles away from where Donald Trump himself was born," she said. "A ban on Muslims would not have stopped this attack. Neither would a wall. I don't know how one builds a wall to keep the Internet out, so not one of Donald Trump's reckless ideas would have saved a single life in Orlando. It's just more evidence that he is temperamentally unfit and totally unqualified to be commander-in-chief."

Clinton has opened up a 12-point lead in a recent national poll over Trump, who officially sewed up the Republican nomination last month. Both have historically high unfavorability ratings.