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Exam 300-420 All Questions

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Exam 300-420 topic 1 question 302 discussion

Actual exam question from Cisco's 300-420
Question #: 302
Topic #: 1
[All 300-420 Questions]

Which AES mode should be used in a Cisco SD-WAN environment that includes multicast applications?

  • A. Electronic Code Book (ECB)
  • B. Cipher Feedback (CFB)
  • C. Cipher Block Chaining (CBC)
  • D. Galois/Counter Mode (GCM)
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Suggested Answer: D 🗳️

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34da117
8 months ago
Selected Answer: C
2024 CCNP Enterprise Design ENSLD Anthony Bruno, Steve Jordan.pdf page368 .... such as in multicast app
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Fibzy
1 year ago
Correct answer is D. "vEdge routers use Advanced Encryption Standard (AES) with a 256-bit key length with the preferred operation Galois/Counter" FROM OCG Mode (GCM)—hence AES-256-GCM. A secondary mode, cipher block chaining (CBC), can be used when required, such as in multicast applications.
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tossaway25
2 months, 1 week ago
Comment contradicts itself. The Cisco SD-WAN white paper and OCG by Bruno both state that GCM is normally used, however CBC is used in the case of multicast. C (CBC) is the definitive answer.
upvoted 1 times
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26d13e9
1 year ago
Selected Answer: D
According to the below link, it depends on the SD-WAN release...go figure....so C and D I guess are both correct in a way or the other.....but will go with D since in C its a combination of CBC and HMAC For multicast traffic: Cisco SD-WAN Release 20.1.x and later– the encryption algorithm is AES-256-GCM Previous releases– the encryption algorithm is AES-256-CBC with SHA1-HMAC https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/security/vedge-20-x/security-book/config-sec-param.html#:~:text=For%20unicast%20traffic%2C%20the%20encryption,algorithm%20is%20AES%2D256%2DGCM
upvoted 2 times
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B (20%)
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