Updated, 8:45 a.m. Friday | Donald J. Trump revealed gaps in his mastery of international affairs during a radio interview on Thursday, appearing to mistake the Quds Force, an Iranian military group, for the Kurds, a Middle Eastern people, and growing testy over questions about foreign leaders.

“You’re asking me names that — I think it’s somewhat ridiculous,” Mr. Trump told Hugh Hewitt, a popular conservative radio show host. “As far as the individual players, of course I don’t know them. I’ve never met them. I haven’t been, you know, in a position to meet them.”

At one point, according to the interview’s transcript, Mr. Hewitt asked Mr. Trump if he was familiar with Gen. Qassim Suleimani, the shadowy commander of Iran’s paramilitary Quds Force.

“Yes, but go ahead, give me a little, go ahead, tell me,” Mr. Trump replied.

“He runs the Quds Forces,” Mr. Hewitt said.

“Yes, O.K., right,” Mr. Trump said.

But Mr. Trump seemed to think Mr. Hewitt was referring to the Kurds, a group with its own language and culture.

Mr. Trump asserted that “the Kurds, by the way, have been horribly mistreated.”

Mr. Hewitt interrupted. “No, not the Kurds, the Quds Forces, the Iranian Revolutionary Guards Quds Forces.”

Mr. Trump tried to recover from the live, on-air tutorial. “Yes, yes,” he said.

He added, “Oh, I thought you said Kurds, Kurds.”

Mr. Trump, a real estate developer and brand manager who has never worked in government, has relatively little experience dealing with foreign governments. But he has boasted of his global reach and international experience as a businessman.

Mr. Hewitt said he was not interested in “gotcha” questions but wanted to be sure Mr. Trump had a baseline of knowledge about foreign leaders.

“On the front of Islamist terrorism, I’m looking for the next commander in chief to know who Hassan Nasrallah is, and Zawahri, and al-Julani, and al-Baghdadi. Do you know the players without a scorecard, yet, Donald Trump?” Mr. Hewitt asked.

Mr. Trump’s answer was strikingly dismissive. “No, you know, I’ll tell you honestly, I think by the time we get to office, they’ll all be changed. They’ll be all gone.”

Making matters worse, Mr. Hewitt asked similar questions on Thursday to Carly Fiorina, a fellow Republican presidential candidate who, like Mr. Trump, has never served in elected office.

But Mrs. Fiorina sounded confident, patient and informed as she discussed the Quds Force, among other subjects.

Asked if she knew the difference between Hamas and Hezbollah, she explained that “Hamas is focused in Palestinian territories. Hezbollah focuses in Beirut and other places, but the truth is, both of them are proxies of Iran. Both of them threaten Israel.”

Mr. Hewitt signaled his approval. “That’s exactly right,” he said.

On the topic of international leaders, Mr. Trump concluded his interview with a touch of his trademark bravado, promising to become an authority on their names as president.

“If they’re still there, which is unlikely in many cases, but if they’re still there, I will know them better than I know you.”

He added, “I will be so good at the military, your head will spin.”