How many bits are in a TCP header?

The correct answer indicates that a standard TCP header is indeed 32 bits in its minimum size. This 32-bit minimum corresponds to the basic TCP header format, which consists of several fields including source port, destination port, sequence number, acknowledgment number, header length, control flags, window size, checksum, and urgent pointer. Each of these fields contributes to the total of 32 bits.

It's important to note that while the header can be extended, the base size remains 32 bits for the basic header structure. The maximum length of a TCP header can extend beyond this minimum if options are included, but again, those options are added to the base 32 bits, not the standard header size itself.

In summary, when considering the TCP header without any added options, it is universally accepted to be 32 bits. This understanding is critical for network design and troubleshooting, as it impacts how packet segmentation and reassembly occur during data transmission.