How many bits is the 'Flags' field in the IPv4 header?

In the IPv4 header, the 'Flags' field is composed of 3 bits. This field plays a critical role in controlling the fragmentation of packets when they traverse a network. The bits within the Flags field are set to regulate how packets are fragmented and reassembled.

The three bits in the Flags field include:

1. Reserved Bit: This bit is reserved for future use and should be set to zero.

2. Don't Fragment (DF) Bit: When this bit is set, it indicates that the packet should not be fragmented. If a router cannot forward the packet due to its size exceeding the Maximum Transmission Unit (MTU) of the next network segment, it will drop the packet and return an error.

3. More Fragments (MF) Bit: This bit is used to indicate whether there are more fragments remaining for fragmentation of the packet. If this bit is set, it tells the receiving system that more fragments will follow.

Understanding the function of the Flags field is crucial for network operations involving packet transmission, especially in scenarios where fragmentation can occur. The 3-bit composition allows for a limited but essential set of control mechanisms to manage how packets are transmitted across diverse network segments.