CISSP Question #239: Real Exam Question with Answer & Explanation

The correct answer is B. Between the delivery header and payload. Generic Routing Encapsulation (GRE) is a protocol that encapsulates a packet of one protocol type within another protocol type. When using GRE tunneling over IPv4, the GRE header is inserted between the delivery header and the payload. The delivery header contains the new source

Submitted by khalil_dz· Mar 5, 2026Communication and Network Security

Question

When using Generic Routing Encapsulation (GRE) tunneling over Internet Protocol version 4 (IPv4), where is the GRE header inserted?

Options

AInto the options field
BBetween the delivery header and payload
CBetween the source and destination addresses
DInto the destination address

Explanation

Generic Routing Encapsulation (GRE) is a protocol that encapsulates a packet of one protocol type within another protocol type. When using GRE tunneling over IPv4, the GRE header is inserted between the delivery header and the payload. The delivery header contains the new source and destination IP addresses of the tunnel endpoints, while the payload contains the original IP packet. The GRE header contains information such as protocol type, checksum, and

Topics

#GRE tunneling#IPv4#network protocols#encapsulation

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