An IPv4 prefix length says how many leading address bits identify a network. For 192.0.2.5/24, the network is 192.0.2.0/24 and the ordinary broadcast address is 192.0.2.255. Configuring that interface commonly installs a connected route, but the prefix is not the entire routing algorithm. The kernel consults routing policy and route tables to select a path for each destination. ...
BGP is the only protocol that stitches tens of thousands of independently operated networks into one forwarding table. It carries reachability, but what it really carries is policy: each network says which prefixes it originates, which neighbours it learned them from, and — through filters — which ones it is willing to pass on. ...
The TCP three-way handshake establishes the two directions of a byte stream. Each endpoint supplies an initial sequence number and acknowledges the other endpoint’s number. Those are independent sequence spaces, not a shared wall clock. Applications do not need synchronized machine clocks to connect. Later sequence numbers identify bytes and support ordering, duplicate handling, acknowledgments, and retransmission within that connection. ...
DHCP hands out leases with a duration, not perpetual ownership. The lifetime drives renewal and lets the server reclaim addresses the device no longer uses. Borrow a number, not own it DHCP does not give a device a permanent address; it lends one for a bounded time. On joining, a client broadcasts to discover a server, and the server offers an address with a lease lifetime defined by the network’s configured lease time. Because the assignment is temporary, the server always knows which addresses are valid and can track them in a pool without guessing. That temporary nature is what makes a large, frequently-changing network manageable: addresses are currency the server can hand out, extend, and take back, rather than addresses a host keeps forever. ...
TCP’s Maximum Segment Size option advertises the receiving endpoint’s maximum TCP data size under the option’s defined accounting rules. Each direction has its own advertisement; the two values need not match. A router can reduce those advertisements while forwarding SYN messages so later data segments fit a constrained path. That changes TCP behavior for the affected connections, not the underlying link MTU itself. ...