echo reply

source quench

route redirection

destination unreachable

Although the answer on here is destination unreachable, but when I went back and check it on my practice final exam through Cisco academy website it said route redirection. Which one is it?

In forming the frame, the MAC layer adds a header and trailer to the Layer 3 PDU.

Purpose of framing:

I. The use of frames aids in the transmission of bits as they are placed on the media and in the grouping of bits at the receiving node.
II. Provides important delimters that are used to identify a group of bits that make up a frame.This process provides synchronization betwen the transmitting and receiving nodes

The encapsulation process also provides for Data Link layer addressing. Each Ethernet header added in the frame contains the physical address (MAC address) that enables a frame to be delivered to a destination node.

An additional function of data encapsulation is error detection. Each Ethernet frame contains a trailer with a cyclic redundancy check (CRC) of the frame contents. After reception of a frame, the receiving node creates a CRC to compare to the one in the frame. If these two CRC calculations match, the frame can be trusted to have been received without error.

2. media access control -contols the frame placement on and off the media
-media recovery