# IP - Internet Protocol * The basic protocol that instructs us on how almost all communication across internet networks must be implemented. * Messages over IP are often communicated in "packets", * which are small bundles of information (2^16 bytes). * Each packet has an essential structure made up of two components: the Header and the Data. * Header * Contains "meta" data about the packet and its data. * his metadata includes information such as * the IP address of the source (where the packet comes from) * the destination IP address (destination of the packet). * an IP Address * layer 3 property * Has Network and Host portion * is a numeric label assigned to each device connected to a computer network that uses the Internet Protocol for communication * There are public and private IP addresses, * there are currently two versions. * IPv6 and is increasingly being adopted because IPv4 (4 bytes = 32 bits) is running out out numerical addresses. * other protocols are built on top of IP, * like frameworks built on languages * Network vs Host * a.b.c.d/x * a,b,c,d are integers * x = defines the network, and the rest as host * Example: 192.168.254.0/24 * the first 24 bits (3 bytes) are network * Max number of networks 2^24 and 2^8 hosts * the rest 8 bits are for host * subnet * subnet has a mask ie 255.255.255.0 * used to determin if IP is in same subnet * Default Gateway * Most networks consist of hosts and a default gateway * when host A want to talk to B directly if both are inthe same subnet, thus use mac address * OW A sends it to someone who might know the gateway * Has an IP add and each host should konw it's gateway * The Beauty of the Internet Protocol hassan nasser --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://hanfak.gitbook.io/workspace/networks/tcp-ip/internet-protocol.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.