Matt Lauer grilled Hillary Clinton on Wednesday evening over her handling of classified information and use of a private email server while she was secretary of state.

Lauer's second question at NBC's Commander-In-Chief Forum was about the email scandal, and he pressed the Democratic presidential nominee as she tried to explain how she handled classified information.

"The word judgment has been used a lot around you, Secretary Clinton, over the last year and a half, and in particular concerning your use of your personal email and server to communicate while you were secretary of state," Lauer said.

He then asked: "Why wasn't it disqualifying, if you want to be commander in chief?"

Clinton repeated past statements about her use of a private server being a mistake.

"As I have said repeatedly, it was a mistake to have a personal account," Clinton said. "I would certainly not do it again. I make no excuses for it. It was something that should not have been done."

She pivoted to defending her assertion that she never mishandled classified information, contrary to FBI Director James Comey's statement saying she was "extremely careless" in handling classified information.

"The real question is the handling of classified material, which is I think what the implication of what your question was," Clinton said. "[I] have a lot of experience dealing with classified material. ... Classified material has a header, which has top secret, secret, confidential. Nothing, and I will repeat this and this is verified in the report by the Department of Justice, none of the emails sent or received by me had such a header."

Lauer pressed on, asking, "Were some of the emails sent or received by you referring to our drone program, our covert drone program?"

"Yes," Clinton responded.

"Of course there were no discussions of any of the covert actions in process being determined about whether or not to go forward," Clinton said. "But every part of our government had to deal with questions, and our secretary of state's office was first and foremost, so there are ways of talking about the drone program in —"

Lauer cut in.

"And you said you thought your communications on that were fairly routine," he said.

Clinton responded, "Well, let me just say, the FBI just released their report about their investigation. They discussed drone matters in the unclassified section of the report."

Lauer pointed out that Comey also said, "there is evidence to support a conclusion that any reasonable person in Secretary Clinton's position should have known that an unclassified system is no place for that conversation."

Clinton noted that experienced foreign-policy experts and defense officials were communicating on an unclassified system.

Lauer pivoted to the question of whether hostile actors could have accessed Clinton's emails that were stored on her private server.

"Matt, there is no evidence, of course anything is possible, but what is factual is the State Department's system was hacked," Clinton said. "Most of the government systems are way behind the curve. We've had hacking repeatedly, even in the White House. There is no evidence my system was hacked."