Dahl was a First-team All-state, All-conference and All-city for Mankato East High School.

Dahl played in 43 games for the Bison and posted 238 tackles (134 solo), 8 passes defensed, 7 interceptions and two sacks.

In 2005, he was Second-team All-Great West and had 71 tackles, an interception forced a fumble and blocked a kick.

In 2004, as a sophomore, he started all 11 games and was named First-team All-Great West Football Conference.

Dahl signed with the New York Giants after playing college football at North Dakota State University.

The move reunited him with Rams head coach Steve Spagnuolo, who was the Giants' defensive coordinator during Dahl's time in New York.