Here we have several fields in a packet mentioned below 🙂

1. Version – Version number (4 bits); predominant version is IP version 4 (IPv4)
2. IP header length – Header length in 32-bit words (4 bits)
3. Precedence and type of service – How the datagram should be handled (8 bits); the first 3 bits are precedence bits (this use has been superseded by Differentiated Services Code Point [DSCP], which uses the first 6 bits [last 2 reserved])
4. Packet length – Total length (header + data) (16 bits)
5. Identification – Unique IP datagram value (16 bits)
6. Flags – Controls fragmenting (3 bits)
7. Fragment offset – Supports fragmentation of datagrams to allow differing maximum transmission units (MTUs) in the Internet (13 bits)
8. Time to Live (TTL) – Identifies how many routers can be traversed by the datagram before being dropped (8 bits)
9. Protocol – Upper-layer protocol sending the datagram (8 bits)
10. Header checksum – Integrity check on the header (16 bits)
11. Source IP address – 32-bit source IP address (32 bits)
12. Destination IP address – 32-bit destination IP address (32 bits)
13. IP options – Network testing, debugging, security, and others (0 or 32 bits, if any)

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