Internet protocol (IPV4) Version 4

Internet Protocol version 4 is the fourth version in the development of the Internet Protocol Internet, and routes most traffic on the Internet.

IPv4 uses 32-bit (four-byte) addresses, which limits the address space to 4294967296 (232) addresses.As addresses were assigned to users, the number of unassigned addresses decreased.

It had been significantly delayed by address changes such as classful network design, Classless Inter-Domain Routing, and network address translation (NAT).

IPv4 reserves special address blocks for private networks (~18 million addresses) and multicast addresses (~270 million addresses).

IANA coordinates allocations from the global IP and AS number spaces, such as those made to Regional Internet Registries.It is US based Organization. Its control IP,MAC or control any others number of network.

  • IP Addresses & AS Numbers
  • Network abuse information

Address representations: 
IPv4 addresses may be written in any notation expressing a 32-bit integer value, but for human convenience, they are most often written in the dot-decimal notation, which consists of four octets of the address expressed individually in decimal and separated by periods.


Fig: IPV4 address Assign


Fig; Divided 32- bits IPV4 per segment 8 bits


An IP address was divided into two parts: Network Address and Host Address 

the network identifier was the most significant (highest order) octet of the address, and the host identifier was the rest of the address. The latter was therefore also called the rest field. This enabled the creation of a maximum of 256 networks.

Allocaton of ip

fig: Allocation of IPv4 address

The system defined five classes, Class A, B, C, D, and E. The Classes A, B, and C had different bit lengths for the new network identification. The rest of an address was used as previously to identify a host within a network, which meant that each network class had a different capacity to address hosts. Class D was allocated for multicast addressing and Class E was reserved for future applications.

IPV4 Address Ranges : 

Class A  ———————–          to 

Class B ————————      to 

Class C————————-      to  

Class D ————————      to   using for multitasking 

Class E ————————     to     reserve for future research 


Starting around 1985, methods were devised to subdivide IP networks. One method that has proved flexible is the use of the variable-length subnet mask (VLSM).

Based on the IETF standard RFC 1517 published in 1993, this system of classes was officially replaced with Classless Inter-Domain Routing (CIDR), and the class-based scheme was dubbed classful, by contrast. CIDR was designed to permit repapartitioning any address space so that smaller or larger blocks of addresses could be allocated to users.

The hierarchical structure created by CIDR is managed by the Internet Assigned Numbers Authority (IANA) and the regional Internet registries (RIRs). Each RIR maintains a publicly searchable WHOIS database that provides information about IP address assignments.

Types of IP Address :

IP address has divided into two parts: 

a) Public IP address : public address using in Gateway / Router for using internet,

b) Private IP address : Private IP address has using into LAN connection.

Private IP and networks: 

Of the approximately four billion addresses allowed in IPv4, three ranges of address are reserved for use in private networks. These ranges are not routable outside of private networks, and private machines cannot directly communicate with public networks. Private IP limit using in LAN inside . 

 Private IP range :




private ip

Virtual private networks:

Packets with a private destination address are ignored by all public routers. Two private networks (e.g., two branch offices) cannot communicate via the public internet, unless they use an IP tunnel or a virtual private network (VPN). When one private network wants to send a packet to another private network, the first private network encapsulates the packet in a protocol layer so that the packet can travel through the public network. Then the packet travels through the public network. When the packet reaches the other private network, its protocol layer is removed, and the packet travels to its destination.

 Optionally, encapsulated packets may be encrypted to secure the data while it travels over the public network.

Link-local address :

RFC 6890 defines the special address block for link-local addressing. hese addresses are only valid on links (such as a local network segment or point-to-point connection) connected to a host. These addresses are not routable. Like private addresses, these addresses cannot be the source or destination of packets traversing the internet.

When the address block was reserved, no standards existed for address autoconfiguration. Microsoft created an implementation called Automatic Private IP Addressing (APIPA), which was deployed on millions of machines and became a de facto standard.

LoopBack / local host address:

The class A network (classless network is reserved for loopback. IP packets whose source addresses belong to this network should never appear outside a host. The modus operandi of this network expands upon that of a loopback interface:

  • IP packets whose source and destination addresses belong to the network (or subnetwork) of the same loopback interface are returned to that interface;
  • IP packets whose source and destination addresses belong to networks (or subnetworks) of different interfaces of the same host, one of them being a loopback interface, are forwarded regularly.

Address Ending in 0 or 255:

Networks with subnet masks of at least 24 bits, i.e. Class C networks in classful networking, and networks with CIDR suffixes /24 to /32 (– may not have an address ending in 0 or 255.

Classful addressing prescribed only three possible subnet masks: Class A, or /8; Class B, or /16; and Class C, or /24. For example, in the subnet ( the identifier commonly is used to refer to the entire subnet. To avoid ambiguity in representation, the address ending in the octet 0 is reserved.

A broadcast address is an address that allows information to be sent to all interfaces in a given subnet, rather than a specific machine. Generally, the broadcast address is found by obtaining the bit complement of the subnet mask and performing a bitwise OR operation with the network identifier. In other words, the broadcast address is the last address in the address range of the subnet. For example, the broadcast address for the network is For networks of size /24 or larger, the broadcast address always ends in 255.

note: In networks smaller than /24, broadcast addresses do not necessarily end with 255. For example, a CIDR subnet has the broadcast address

Address Resolution : Domain Name system

Hosts on the Internet are usually known by names, e.g.,, not primarily by their IP address, which is used for routing and network interface identification. The use of domain names requires translating, called resolving, them to addresses and vice versa.

The translation between addresses and domain names is performed by the Domain Name System (DNS), a hierarchical, distributed naming system which allows for subdelegation of name spaces to other DNS servers.

Packet Structure :

An IP packet consists of a header section and a data section.An IP packet has no data checksum or any other footer after the data section. Typically the link layer encapsulates IP packets in frames with a CRC footer that detects most errors, and typically the end-to-end TCP layer checksum detects most other errors.

Header :

The IPv4 packet header consists of 14 fields, of which 13 are required. The 14th field is optional (red background in table) and aptly named: options. The fields in the header are packed with the most significant byte first (big endian), and for the diagram and discussion, the most significant bits are considered to come first (MSB 0 bit numbering). The most significant bit is numbered 0, so the version field is actually found in the four most significant bits of the first byte, for example.

Version The first header field in an IP packet is the four-bit version field. For IPv4, this has a value of 4 (hence the name IPv4).

Related Topics :

  • Intranet is shared content accessed by members within a single organization.(An intranet is a private computer network that uses Internet Protocol technologies to securely share any part of an organization’s information or operational systems within that organization)
  • Extranet is shared content accessed by groups through cross-enterprise boundaries.(An extranet is a private network that uses Internet protocols, network connectivity. An extranet can be viewed as part of a company’s intranet that is extended to users outside the company, usually via the Internet.)
  • Internet is global communication accessed through the Web.(The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide.)
  • A local area network (LAN) is a computer network that interconnects computers within a limited area such as a home, school, computer laboratory, or office building, using network media. Its need Mac address of every connected computers for communication and Its used Switch as Intermediary Device. For LAN connection IP address is not necessary .LAN should have to same network address. 
  • A router is a networking device, commonly specialized hardware, that forwards data packets between computer networks. This creates an overlay internetwork, as a router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the “traffic directing” functions on the Internet. Router is called Gateway when need to connect Internet.

Thank you

Momataj Momo


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