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CCIE Sec Encryption Ipsec

Subjects : cisco, it-skills, ccie
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. It also provides protection for ISAKMP peer identities with encryption.






2. Used in IPsec for two discreet purposes:






3. 'algorithm encrypts and decrypts data three times with 3 different keys - effectively creating a 168-bit key.'






4. 'A 56-bit encryption algorithm - meaning the number of possible keys






5. A






6. The DES algorithm that performs 3 times sequentially.






7. IPsec implements using a shim header between L2 and L3






8. Provides authentication and encryption of the payload.






9. 'Finally - the receiving devices decrypt the data with the first key.'






10. Main disadvantage of asymmetric algorithms is that they are slow.






11. 'often called public-key algorithms - do not rely on a randomly generated shared encryption key; instead - they create two static keys. These static keys are completely different - but mathematically bound to each other; what one key encrypts - the o






12. Data integrity is the process of making sure data is not tampered with while it






13. 'key lengths are 128 - 192 - or 256 bits to encrypt blocks of equal length.'






14. The receiving device then encrypts the data with the second key.






15. ' is defined in RFC 3174. has as output a 160-bit value -'






16. 'When using the hash-based key function -'






17. Uses the D-H algorithm to come to agreement over a public network.






18. Turns clear-text data into cipher text with an encryption algorithm. The receiving station decrypts the data from cipher text into clear text. The encryption key is a shared secret key that encrypts and decrypts messages.






19. Uses IKE for key exchange.






20. 'key exchange is vulnerable to a man-in-the-middle attack. You can rectify this problem by allowing the two parties to authenticate themselves to each other with a shared secret key - digital signatures - or public-key certificates.'






21. 'Message digest algorithms have a drawback whereby a hacker (man in the middle) can intercept a message containing the packet and hash values - then re-create and transmit a modified packet with the same calculated hash to the target destination.'






22. Can be implemented efficiently on a wide range of processors and in hardware.






23. No additional Layer 3 header is created. The original Layer 3 header is used.






24. 'Encryption - where Peer X uses Peer Y






25. Main mode establishes ISAKMP security association in six messages and performs authenticated D-H exchange.






26. The protocol of choice for key management and establishing security associations between peers on the Internet.






27. Negotiation of the ISAKMP policy by offering and acceptance of protection suites

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28. IPSEC tunnels data through IP using one of two protocols?






29. 'establishes ISAKMP SA in three messages -because it negotiates a ISAKMP policy and a DJ nonce exchange together.'






30. You use this encryption method by keeping one key private and giving the other key to anyone in the public Internet. It does not matter who has your public key; it is useless without the private key.






31. Does not provide payload encryption.






32. Origin authentication validates the origin of a message upon receipt; this process is done during initial communications.






33. 'is a block-cipher algorithm - which means that it performs operations on fixed-length data streams of 64-bit blocks. The key ostensibly consists of 64 bits; however - only 56 are actually used by the algorithm.'






34. Hybrid protocol that defines the mechanism to derive authenticated keying material and negotiation of security associations (SA).






35. The sending device encrypts for a final time with another 56-bit key.






36. 'group 5 identifies a 1536-bit key - provides for highest security but is the slowest of all groups.'






37. That authenticate data packets and ensure that data is not tampered with or modified.






38. Is a two-phase protocol: The first phase establishes a secure authenticated channel and the second phase is where SAs are negotiated on behalf of the IPsec services.






39. Integrity checks are done

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40. 'group 2 identifies a 1024-bit key - group 2 is more secure - but slower to execute.'






41. IPSec SAs are negotiated and protected by the existing IPsec SA.






42. RFC 2631 on the workings of the key generation/exchange process.






43. 'Three keys encrypt the data - which results in a 168-bit encryption key. The sending device encrypts the data with the first 56-bit key.'






44. Negotiation of the ISAKMP policy by offering and acceptance of protection suites






45. 'It is not used for encryption or digital signatures; it is used to obtain a shared secret






46. Where the original Layer 3 header and payload inside an IPsec packet is encapsulated. Tunnel mode does add overhead to each packet and uses some additional CPU resources.






47. 'produces a 160-bit hash output - which makes it more difficult to decipher.'






48. Uses protocol number 51.






49. 'Created by NIST in 1994 - is the algorithm used for digital signatures but not for encryption.'






50. More CPU intensive