Primary to Rental to Primary Tax Implications

[Robert Wong]

Hi, 

I'm looking for clarification on the following scenario:

I buy and live in a house as my primary residence for 2 years. Then, I convert it to a rental for the next 5 years. Finally, I decide to return and change the rental back to my primary residence for 2 more years. I subsequently sell the house and have capital gains of $100K. 

Under this scenario, am I exempt from paying capital gains tax on the $100K? Or would I have to pro-rate it based on number qualified vs non-qualified use?