Which two statements about GRE tunnels are true?

GRE, or Generic Routing Encapsulation, is a protocol used to encapsulate a wide variety of network layer protocols into point-to-point links. One of the key features of GRE is its ability to tunnel non-IP protocols, which includes protocols like IPX. This makes it versatile in environments where multiple network protocols are used, allowing different types of traffic to be sent across an IP network.

While getting into the technical details, GRE is particularly well-suited for tunneling IPv4 and IPv6 packets, as well as non-IP protocols like IPX. The ability to encapsulate these various protocols is pivotal, especially in legacy systems or in specialized configurations where non-standard protocols are present.

Additional details about the other statements provide context: GRE itself does not provide encrypted communication; it simply encapsulates packets without any built-in security features. Encryption can be achieved with other protocols like IPsec, which can work alongside GRE. Furthermore, GRE adds an overhead of 24 bytes per packet, consisting of an additional GRE header, which impacts the overall packet size. Lastly, GRE can indeed tunnel IPv6 traffic, but the focus of the correct statement highlights its capability to handle non-IP protocols, which sets it apart in multi-protocol situations.