What is the name of the RSA public key file used for authentication in remote connections?

The correct choice is the file named id_rsa.pub. This file contains the public key component of an RSA key pair. When using public key authentication for remote connections, the public key is shared with the server you want to connect to, while the corresponding private key (stored in id_rsa) remains confidential on your local machine.

When you attempt to log into a remote server, the server uses the public key (id_rsa.pub) stored in the authorized_keys file on that server to verify if you own the private key. If the keys match, you gain access without needing to enter a password, provided that your private key is correctly configured.

In this context, it’s important to note that other files, such as id_rsa, contain the private key and should remain secure and not be shared openly. The authorized_keys file is where the public keys of authorized users are stored on the server, but it is not the public key file itself. The term pub_key is not a standard naming convention and does not correspond to a specific file typically used for public key authentication in SSH contexts.