What technology is used to carry IPv6 packets across an IPv4 network?

The use of Generic Routing Encapsulation (GRE) Tunnels is indeed the correct choice for carrying IPv6 packets across an IPv4 network. GRE is a tunneling protocol that encapsulates a wide variety of network layer protocols into point-to-point connections. It allows packets from one protocol to be transported over a different protocol, making it suitable for situations where you need to bridge two different networking architectures.

By encapsulating IPv6 packets within GRE tunnels, organizations can facilitate communication between IPv6-only sites over an existing IPv4 infrastructure. This is particularly important in transitional scenarios where full IPv6 deployment might not yet be possible, enabling IPv6 traffic to traverse IPv4 networks seamlessly.

While the other options present important technologies in networking and security, they do not specifically serve the role of encapsulating IPv6 packets for transit over an IPv4 network. A Virtual Private Network (VPN) is primarily for secure point-to-point connections and does not specifically address protocol encapsulation. Transport Layer Security (TLS) is a cryptographic protocol designed mainly for securing communications over a network and is not a tunneling mechanism. Internet Protocol Security (IPsec) provides encryption and secure authentication for Internet Protocol (IP) communications but can be considered a more general security protocol rather than a specific