Answer:
No, the receiver cannot be absolutely certain that no bit errors have occurred. This is because of the manner in which the checksum for the packet is calculated. If the corresponding bits (that would be added together) of two 16-bit words in the packet were 0 and 1 then even if these get flipped to 1 and 0 respectively, the sum still remains the same. Hence, the 1s complement the receiver calculates will also be the same. This means the checksum will verify even if there was transmission error
Explanation:
Watchdog Program
This program becomes the number one security mechanism for file access.
Pros:
- A benefit of using watchdog program is that you have a centralized mechanism for controlling access to a file
- You are assured of having secure access to your file
Cons:
- It becomes a bottleneck.
- If this program has a security hole, there are no other guaranteed backup mechanisms for file protection.
COPS
COPS is a collection of a dozen programs that attempt to tackle problems in UNIX security. It checks for a number things like poor passwords, device permissions, files run in /etc/rc*, existence of root SUID, and many other things.
Pros:
- This program provides methods of checking for common procedural errors.
- COPS collect outputs and either mails the information to the admin or logs it in.
Cons:
- It could be modified by an intruder or even take advantage of its features.
- It is meant to tighten the security, not a tool to be used to find security flaws. It does not directly correct errors found.
The answer is T
Explanation: I just took the test :)
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