What is Vault 101?
Vault 101 is an Vault-Tec Vault designed withinitial flaws to begin with. The flaws of Vault 101 is the fact that its main doors were never designed to open. In essence, the programing of the vault door never had any reverse opening protocol, which I can assume was hacked by your father on fallout 3. It is one out of 122 vaults that Vault-Tec built with money from goverment firms.