Which encryption protocol is commonly used for securing internet traffic?

The correct answer is IPSec because it is specifically designed to secure Internet Protocol communications by authenticating and encrypting each IP packet within a communication session. IPSec operates at the network layer, which allows it to protect all traffic traversing the network without requiring any changes to applications. This versatility makes it a popular choice for creating Virtual Private Networks (VPNs), ensuring that data transmitted over the internet is secure from eavesdropping and tampering.

HTTP, on the other hand, is a protocol used for transmitting hypertext via the World Wide Web, but it does not inherently provide security. While there is a secure version known as HTTPS, that utilizes SSL/TLS rather than IPSec.

FTP is a protocol for transferring files over the internet, but it also lacks built-in security features, making it unsuitable for securing internet traffic without additional layers like FTPS or SFTP.

SMTP, or Simple Mail Transfer Protocol, is used for sending emails and does not provide encryption for securing email during transmission, again requiring additional protocols such as SMTPS for secure email transmission.

In summary, IPSec stands out as the encryption protocol specifically tailored for securing internet traffic and ensuring the confidentiality and integrity of data as it moves across potentially unsecured networks.