Ace the Cisco ENCOR Challenge 2026 – Unleash the Networking Pro in You!

When using GRE (Generic Routing Encapsulation), a total of 4 bits are added to the packet header for the GRE protocol implementation. This includes two fields: the "Flags" field, which takes up 2 bits, and the "Protocol Type" field, which uses 16 bits for identifying the encapsulated protocol. Thus, while the total header size includes additional fields and protocols, the specific addition that is relevant to GRE's main header is 4 bits for its flags.

This encapsulation is pivotal in the functioning of GRE, as it allows for the encapsulation of various types of protocols over an IP network, thereby facilitating the creation of virtual point-to-point links. Knowing the specifics of header sizes in protocols like GRE is essential for network design and troubleshooting, as it impacts the overall efficiency and performance of data encapsulation techniques.