Cisco Certified Network Associate (CCNA) Practice Exam

Which type of key encryption is preferable for encrypting large data before transfer over a VPN?

1. Asymmetric Key Cryptography

2. Symmetric Key Cryptography

3. Hash Function Cryptography

4. Secure Hash Algorithm

The correct answer is: Symmetric Key Cryptography

When considering encryption methods for large data transfers over a VPN, symmetric key cryptography is the preferred option. This preference is primarily due to its operational efficiency in processing large volumes of data. Symmetric key cryptography uses a single key for both encryption and decryption. This method typically requires less computational power compared to asymmetric key cryptography, which uses a pair of keys (a public key for encryption and a private key for decryption). The mathematical complexity involved in asymmetric encryption algorithms means that they generally require more processing time, making them less suitable for encrypting large datasets quickly. In addition, symmetric algorithms such as AES (Advanced Encryption Standard) are specifically designed to handle large amounts of data efficiently, providing a good balance between security and performance. Due to their design, symmetric algorithms can encrypt and decrypt data rapidly, which is crucial when large files need to be transmitted securely over a VPN. Other options like hash functions and secure hash algorithms do not provide encryption, as they are used for data integrity verification and not for protecting data confidentiality. Hash functions produce a fixed-size output (hash) from data, allowing the verification of data integrity but not allowing the original data to be retrieved. This makes them unsuitable for the purpose of encrypting data for transfer. In