> For the complete documentation index, see [llms.txt](https://mudassirs46.gitbook.io/network-fundamentals/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mudassirs46.gitbook.io/network-fundamentals/ipv4.md). # IPv4: [Internet Protocol](https://app.gitbook.com/@mudassirs46/s/network-fundamentals/~/drafts/-MRZ8l67L5MHnaQIEh9W/ip-internet-protocol) Version 4 is a L3 Network Protocol of 4 Bytes 32 bits Decimal Address which can produce over 4 Billion (4,294,967,296) Unique Addresses. * This 32-bit IPv4 Address is divided into 4 parts called Octets (each of 1 byte/8 bit) * Those bits in each Octet are represented by a number. Starting from the left they have a value of 128, 64, 32, 16, 8, 4, 2, 1. * Each bit on the octet can be either 1 or 0. If a Number is 1 then that octet is counted if it is a 0 then it is ignored. * Just by manipulating 1s & 0s in each octet, we get a range from 0-255. * **IPv4 Header:** * It is a connectionless Protocol that offers only best-effort delivery. * Each packet is treated differently hence packets may take different paths based on options like Hop Count, Load Balancing, or Bandwidth offered by different Routing Protocols. * IP has no Data Recovery, No built-in Sessions & No Re-transmission features. Hence, L3 Internet Protocol relies on the L4 TCP which offers all these features & provides guaranteed delivery of Data & packets. * Routers route packets based on NID & not HID. * IPv4 Address is divided into [2 parts](https://app.gitbook.com/@mudassirs46/s/network-fundamentals/~/drafts/-MRZ8l67L5MHnaQIEh9W/ipv4-address-parts): * Network Port (NID) * Host Portion (HID) * IPv4 Classfull Addresses were divided into 5 [Classes](https://app.gitbook.com/@mudassirs46/s/network-fundamentals/~/drafts/-MRZ8l67L5MHnaQIEh9W/ipv4-address-classes-1) ## Reference: * * CCNA 200-301 OCG, Volume 1, Pg. 74 - Wendell Odom .