Ethernet Frame Components | CCNA Exam Preparation

Ethernet Frame Components

Question

Which component of an Ethernet frame is used to notify a host that traffic is coming?

Answers

Explanations

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A. B. C. D.

C.

Preamble is a 7 Byte field in the Ethernet frame which helps to receiver to know that it is an actual data (Ethernet Frame) and not some random noise in the transmission medium.

It acts like a doorbell telling about the incoming data.

The component of an Ethernet frame that is used to notify a host that traffic is coming is the preamble.

The preamble is an 8-byte field that is added to the beginning of an Ethernet frame. It is made up of a sequence of alternating 0s and 1s, which serves as a synchronization pattern that alerts the receiving device that data is about to be transmitted.

When the receiving device detects the preamble, it knows that an Ethernet frame is incoming and can then synchronize its clock to the incoming data. This helps to ensure that the data is received without errors.

The start of frame delimiter (SFD) is another field in the Ethernet frame, but its purpose is slightly different from the preamble. The SFD immediately follows the preamble and is a fixed 1-byte value that indicates the start of the Ethernet frame's data field.

The type field is a 2-byte field that comes after the destination and source MAC addresses in the Ethernet frame header. It indicates the type of protocol that is encapsulated in the data field of the Ethernet frame.

The data field is the part of the Ethernet frame that contains the actual data being transmitted, such as an IP packet or another protocol's data. It comes after the header fields (destination and source MAC addresses, type field, and optional VLAN tag) and is followed by the frame check sequence (FCS), which is a 4-byte field that contains a cyclic redundancy check (CRC) value used for error detection.