What can be used to encrypt data in flight between untrusted locations?

Question

Options

• AOSPF authentication
• BMACSec
• CGRE tunnels
• DMD5 encryption

• A
  4% (1)
• B
  93% (25)
• C
  4% (1)

Explanation

MACSec (802.1AE) provides hop-by-hop encryption at Layer 2, making it suitable for encrypting data in transit between untrusted network segments - it encrypts the actual payload as frames traverse links, protecting against eavesdropping at the wire level.

Why the others are wrong:

• A. OSPF authentication only verifies the identity of routing peers (using MD5 or SHA); it authenticates routing updates but does not encrypt data traffic.
• C. GRE tunnels encapsulate packets but provide no encryption on their own - you'd need to pair GRE with IPSec to get actual data confidentiality.
• D. MD5 "encryption" is a trap: MD5 is a hashing algorithm, not an encryption mechanism, and it's used for integrity checking, not confidentiality.

Memory tip: Think of MACSec = MAC-layer Security. It's the only option here that actually encrypts at the data-link layer. If you see "encrypt data in flight" combined with Layer 2 or untrusted links, MACSec is almost always the answer - GRE without IPSec is the classic distractor because tunneling feels like it should be secure, but it's just wrapping, not encrypting.

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