Networking Job Interview Questions and Answers – Page 10

Networking Job Interview Questions and Answers – Page 10
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65. What is Brute Force Attacks?

Answer: A brute-force attack may refer to a password and cryptography attack that does not attempt to decrypt any information, but continue to try a list of different passwords, words, or letters. In general, it is a method used by application programs to decode encrypted data such as passwords or Data Encryption Standard (DES) keys.

The automated software can run billions of combinations of letters, numbers, and symbols over and over until it becomes statistically correct and cracks the code. Once the correct username and password combination is found, the attacker is able to access the secure data.


66. What are the Data link protocols?

 Answer: Data-link layer is responsible for implementation of point-to-point flow and error control mechanism. Data link protocols are sets of specifications used to implement the data link layer. These protocols include token ring, FDDI, and Ethernet. Data link protocols may provide any of the following services:

  •  Framing
  •  Session setup and termination
  •  Error detection
  •  Addressing on a multipoint medium such as a LAN
  •  Flow control

The categories of Data Link protocols are :

  •  Asynchronous Protocols
  •  Synchronous Protocols:
    a. Character Oriented Protocols
    b. Bit Oriented protocols

67. What is Forward Error Correction?  – Networking

 Answer: Forward error correction is the process in which the receiver tries to guess the message by using redundant bits.


68. What is Retransmission?  – Networking

 Answer: Retransmission is a technique in which the receiver detects the occurrence of an error and asks the sender to resend the message. Resending is repeated until a message arrives that the receiver believes is error-freed.

 Retransmission is one of the basic mechanisms used by protocols operating over a packet switched computer network to provide reliable communication, eg. TCP. Whenever one party sends something to the other party, it retains a copy of the data it sent until the recipient has acknowledged that it received it.


69. At what time frequency are the retransmission requests performed? – Networking

 Answer: The retransmissions-times and the number of attempts aren’t enforced by the standard. It is implemented differently by different operating systems, but the methodology is fixed. (One of the ways to fingerprint OSs perhaps?)

The timeouts are measured in terms of the RTT (Round Trip Time) times. But this isn’t needed very often due to Fast-retransmit which kicks in when 3 Duplicate ACKs are received.


70. What do you mean by Multi-homed Host?  – Networking

 Answer: It is a multiple network interface that requires multiple IP addresses.


71. What do you mean by  External Data Representation. ?  – Networking

 Answer: It is a method of encoding data within an RPC message. It is used to ensure that the data is not system-dependent.


72. Which transmission medium works at 2 Giga bits per second.  – Networking

Answer: The fiber cable sends data at the rate of 2 Giga bytes per second. The cable consists of Hair like thin fiber which works on the principle of total internal reflection. It transmits data with speed of light and works on bandwidth up to terahertz.Transmitting medium is the fiber of glass which is insulated on the outside.

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