Checking For A Natural

If the dealer’s upcard in blackjack is an ace or any ten-value card, she peeks at her downcard to see if she has a natural. If she does, the hand is terminated and everyone loses automatically, except those players who also have naturals. Remember, when the dealer and a player both have naturals, it is considered a push and no money changes hands.
Since a dealer’s natural is settled at the beginning of a round, the players never have an opportunity to increase their bets by doubling or splitting. Consequently, any player who doesn’t also have a natural only loses his initial wager.
Advance knowledge of the dealer’s downcard is of great benefit to a player, so when the dealer peeks, there is always the danger of cheating. A dishonest dealer may signal the value of the hole card to a confederate at the table, or a player may get a glimpse of it. To prevent these things from happening, some casinos have changed the peeking rules. Sometimes the dealer may only peek if the upcard is an ace, and sometimes she isn’t supposed to peek at all.
When the dealer doesn’t peek or only peeks under aces, a dealer’s natural may not be apparent until everyone has finished playing out his hand. What about those players who increased their bets by doubling or splitting? In the United States, the extra bets are ignored and the players only lose their initial wagers.