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






2. 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.






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






4. 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.






5. 'Encryption - where Peer X uses Peer Y






6. 'provides everything required to securely connect over a public media - such as the Internet.'






7. A variable block- length and key-length cipher.






8. 'including Internet Security Association and Key Management Protocol (ISAKMP) - Secure Key Exchange Mechanism for the Internet (SKEME) - and Oakley.'






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






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






11. Uses protocol number 50.






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






13. IPSEC performs this function by using a sequence field in the IPsec header combined with integrity checks.






14. It uses UDP 500 and is defined by RFC 2409.






15. One of the most popular tunneling protocols is






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






17. A






18. 'is a more secure version of MD5 - and hash-based message authentication codes (HMAC) provides further security with the inclusion of a key-based hash.'






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

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20. 'The sending device decrypts the data with the second key - which is also 56 bits in length.'






21. '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.'






22. Verify whether the data has been altered.






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






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






25. The receiving device decrypts the data with the third key.






26. 'can be achieved using one of three methods: preshared keys - encrypted nonces - or digital signatures.'






27. Provides authentication and encryption of the payload.






28. Invented by Ron Rivest of RSA Security (RFC 1321).






29. ID exchange and authentication of D-H key by using the reply to the received nonce or string of bits

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30. 'in most cases - this mode is preferred with certificates.'






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






32. Does not provide payload encryption.






33. Drawback of this is that the hash is passed unencrypted and is susceptible to PSK crack attacks.






34. '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.'






35. '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.'






36. Negotiation of a shared secret key for encryption of the IKE session using the D-H algorithm

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






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






39. Act of encapsulating a packet within another packet.






40. Used in IPsec for two discreet purposes:






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






42. 'defines the mode of communication - creation - and management of security associations.'






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






44. DoS attacks are more probable with this mode.






45. 'MACs with hash algorithms -'






46. This mode does not support identity protection or protection against clogging attacks and spoofing.






47. '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.'






48. '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






49. Integrity checks are done

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50. More CPU intensive