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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. 'MACs with hash algorithms -'






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






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






4. Has a trailer which identifies IPsec information and ESP integrity-check information.






5. IPSEC Encryption is performed by

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






7. 'requires that the sender and receiver have key pairs. By combining the sender






8. Benefits are that the preshared authentication can be based on ID versus IP address and the speed of the process.






9. 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.






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






11. Used in IPsec for two discreet purposes:






12. 'DSA is roughly the same speed as RSA when creating signatures - but 10 to 40 times slower when verifying signatures. Because verification happens more frequently than creation - this issue is worth noting when deploying DSA in any environment.'






13. 'Encryption - where Peer X uses Peer Y






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






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






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






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






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






19. 'group 1 identifies a 768-bit key - group 1 is faster to execute - but it is less secure -'






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

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






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






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






24. Uses IKE for key exchange.






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






26. '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.'






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






28. Common key size is 1024 bits.






29. Does not provide payload encryption.






30. 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.






31. '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.'






32. It also provides protection for ISAKMP peer identities with encryption.






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






34. '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.'






35. More CPU intensive






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






37. Message of arbitrary length is taken as input and produces as output a 128-bit fingerprint or message digest of the input.






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






39. '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.'






40. '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






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






42. 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.






43. Provide authentication in Internet Key Exchange (IKE) Phase 2.






44. Uses protocol number 51.






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






46. One of the most popular tunneling protocols is






47. Takes variable-length clear-text data to produce fixed-length hashed data that is unreadable.






48. DoS attacks are more probable with this mode.






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






50. Used for integrity checks on peer and data sent by peer and for authentication checks.