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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. IPSEC Encryption is performed by

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






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






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






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






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






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






8. '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.'






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






10. More CPU intensive






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






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






13. A






14. 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.






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






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






17. '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.'






18. Uses protocol number 51.






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






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






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






22. Act of encapsulating a packet within another packet.






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






24. '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.'






25. Provides authentication and encryption of the payload.






26. One of the most popular tunneling protocols is






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






28. 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.






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






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






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

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






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






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






35. '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.'






36. Does not provide payload encryption.






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






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






39. 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.






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






41. Verify whether the data has been altered.






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






43. Integrity checks are done

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44. '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






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






46. 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.






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






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






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






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