The IPv4 header has several fields, as shown in the following diagram:
Some of the fields are rarely used, such as those that deal with fragmentation. Others provide information that can help with troubleshooting, such as the address fields when resolving network conflicts.
To examine an IPv4 header, open bigFlows.pcap, and go to frame 1, as shown here:
The following section will list each field, and how many bits or bytes are used in each field, along with information ...