Some sites choose not to implement Trivial File Transfer Protocol (TFTP) due to the inherent security risks. TFTP is a UDP-based file transfer program that provides no security. There is no user authentication.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 88.

A network-based IDS usually provides reliable, real-time information without
consuming network or host resources.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 48.

Explanation/Reference:
Physical security and environmental security are part of operational controls, and are measures taken to protect systems, buildings, and related supporting infrastructures against threats associated with their physical environment. All the questions above are useful in assessing physical and environmental protection except for the one regarding processes that ensuring that unauthorized individuals cannot access information, which is more a production control.
Source: SWANSON, Marianne, NIST Special Publication 800-26, Security Self-Assessment Guide for Information Technology Systems, November 2001 (Pages A-21 to A-24).

A given message and key always produce the same ciphertext.
The following answers are incorrect:
Repetitive encryption obscures any repeated patterns that may have been present in the plaintext. Is incorrect because with Electronic Code Book a given 64 bit block of plaintext always produces the same ciphertext
Individual characters are encoded by combining output from earlier encryption routines with plaintext. This is incorrect because with Electronic Code Book processing 64 bits at a time until the end of the file was reached. This is a characteristic of Cipher Feedback. Cipher Feedback the ciphertext is run through a key-generating device to create the key for the next block of plaintext.
The previous DES output is used as input. Is incorrect because This is incorrect because with Electronic Code Book processing 64 bits at a time until the end of the file was reached . This is a characteristic of Cipher Block Chaining. Cipher Block Chaining uses the output from the previous block to encrypt the next block.