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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. '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.'






2. Common key size is 1024 bits.






3. '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.'






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






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






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






7. Act of encapsulating a packet within another packet.






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






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






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






11. 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.






12. Integrity checks are done


13. You check it by hashing data and appending the hash value to the data as you send it across the network to a peer.






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






15. '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.'






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






17. Uses IKE for key exchange.






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






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






20. 'has a Next Protocol field which identifies the next Layer 4 transport protocol in use - TCP or UDP'






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






22. Uses protocol number 51.






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






24. 'Encryption - where Peer X uses Peer Y






25. Verify whether the data has been altered.






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






27. Used in IPsec for two discreet purposes:






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






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






30. Key exchange for IPSEC






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






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


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






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






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






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


37. Does not provide payload encryption.






38. Uses protocol number 50.






39. 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.






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






41. 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.






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






43. DoS attacks are more probable with this mode.






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


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






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






47. More CPU intensive






48. 'Developed in 1977 by Ronald Rivest - Adi Shamir - and Leonard Adleman (therefore - RSA).'






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






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