At what layer of the OSI model do the IP, ICMP, and ARP protocols operate?

The purpose of a(n) ____________________ field is to accept entries containing text, numbers, and/or symbols.

Fill in the blank(s) with the appropriate word(s).

An NMS can tell an agent to make changes to the information it queries and sends, called variables, through a __________ protocol data unit (PDU).

A. Set B. Get C. Response D. Trap