What are the drivers' last names who had 11 pit stops?
SELECT T1.surname ,  T1.driverid FROM drivers AS T1 JOIN pitstops AS T2 ON T1.driverid   =   T2.driverid GROUP BY T1.driverid HAVING count ( * )    =   11
drivers' last names refers to surname from drivers; had 11 pit stops refers to COUNT(*) = 11 from pitstops;