Multiple customer sites are connected through your service provider network using a Layer 3 VPN. You must design the Layer 3 VPN so that the traffic sent between sites is encrypted. Which technology…

Question

Options

• AUse IPsec with AH.
• BUse GRE with a key sequence number.
• CUse IPsec with ESP.
• DUse OSPF with IPsec authentication.

• A
  5% (2)
• B
  14% (6)
• C
  74% (32)
• D
  7% (3)

Explanation

IPsec with ESP (Encapsulating Security Payload) is correct because ESP provides both encryption and authentication, making it the only option here that actually encrypts traffic - which is the explicit requirement. Option A (IPsec with AH) is wrong because AH (Authentication Header) only provides authentication and integrity, not encryption. Option B (GRE with a key sequence number) only adds a simple identifier for tunnel demultiplexing - the key is not a cryptographic key and provides zero encryption. Option D (OSPF with IPsec authentication) secures routing protocol exchanges, not the data-plane traffic flowing between customer sites.

Memory tip: Think "ESP = Encryption, Security, Privacy" - if the question asks for encryption in a VPN context, ESP is your answer. AH is the "authentication-only" cousin that often appears as a distractor alongside ESP.

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