Cisco Certified Network Associate (CCNA) Practice Exam

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Study for the Cisco Certified Network Associate (CCNA) exam with our comprehensive quiz featuring multiple-choice questions and detailed explanations. Prepare effectively and enhance your understanding of networking concepts!

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What is the block size that the Data Encryption Standard (DES) operates on?

32 bits
56 bits
64 bits
128 bits

The correct answer is: 64 bits

The Data Encryption Standard (DES) operates on a block size of 64 bits. This means that when data is encrypted using DES, it is processed in blocks of this size. Each block undergoes a series of transformation rounds to encrypt the data securely. The 64-bit block size allows DES to handle larger amounts of data in each encryption operation, making it efficient within its design scope. In contrast to the correct answer, options like 32 bits and 56 bits refer to other aspects of encryption, such as key lengths or characteristics of different encryption algorithms. For instance, while DES uses a key length of 56 bits for encryption, the block size is distinctly 64 bits, and that is crucial for the block-oriented processing nature of the DES algorithm. The 128-bit option does not apply to DES as it's characteristic of newer encryption standards like AES (Advanced Encryption Standard).