When are the two Rak'ahs of the Fajr Sunnah to be prayed by one who missed the congregational Fajr prayer due to sleep or other reasons: Are they to be prayed before or after the Fajr prayer?

If a Muslim is late for the congregational Fajr prayer, he should begin with the regular Sunnah prayer, then pray Fajr. This is what the Prophet (peace be upon him) did when he missed the Fajr prayer during a journey; he ordered the Adhan and Iqamah as usual. However, if a Muslim comes to the mosque and finds the congregation already praying, and he joins them without having prayed the regular Sunnah, he can pray it after the obligatory prayer as a make-up (qada'), or after the sun has risen. Both are permissible, though praying it after the sun has risen is better.