IPv4 addresses are actually 32-bit binary numbers, consisting of the two subaddresses (identifiers) mentioned above which, respectively, identify the network and the host to the network, with an imaginary boundary separating the two. An IP address is, as such, generally shown as 4 octets of numbers from 0-255 represented in decimal form instead of binary form. Show For example, the address 168.212.226.204 represents the 32-bit binary number 10101000.11010100.11100010.11001100. The binary number is important because that will determine which class of network the IP address belongs to.
192.168.17.43 IPv4 addresses are composed of two parts. The first numbers in the address specify the network, while the latter numbers specify the specific host. A subnet mask specifies which part of an address is the network part, and which part addresses the specific host. A packet with a destination address that is not on the same network as the source address will be forwarded, or routed, to the appropriate network. Once on the correct network, the host part of the address determines which interface the packet gets delivered to. Subnet masksA single IP address identifies both a network, and a unique interface on that network. A subnet mask can also be written in dotted decimal notation and determines where the network part of an IP address ends, and the host portion of the address begins. When expressed in binary, any bit set to one means the corresponding bit in the IP address is part of the network address. All the bits set to zero mark the corresponding bits in the IP address as part of the host address. The bits marking the subnet mask must be consecutive ones. Most subnet masks start with 255. and continue on until the network mask ends. A Class C subnet mask would be 255.255.255.0. IP address classesBefore variable length subnet masks (introduced with RFC-1519 in 1993) allowed networks of almost any size to be configured regardless of the actual address, the IPv4 address space was broken into five classes as follows: ClassLeading Class A In a Class A network, the first eight bits, or the first dotted decimal, is the network part of the address, with the remaining part of the address being the host part of the address. There are 128 possible Class A networks. 0.0.0.0 to 127.0.0.0 However, any address that begins with 127. is considered a loopback address. Example for a Class A IP address: 2.134.213.2
In a Class B network, the first 16 bits are the network part of the address. All Class B networks have their first bit set to 1 and the second bit set to 0. In dotted decimal notation, that makes 128.0.0.0 to 191.255.0.0 as Class B networks. There are 16,384 possible Class B networks. Example for a Class B IP address: 135.58.24.17
In a Class C network, the first two bits are set to 1, and the third bit is set to 0. That makes the first 24 bits of the address the network address and the remainder as the host address. Class C network addresses range from 192.0.0.0 to 223.255.255.0. There are over 2 million possible Class C networks. Example for a Class C IP address: 192.168.178.1 Class D Class D addresses are used for multicasting applications. Unlike the previous classes, the Class D is not used for "normal" networking operations. Class D addresses have their first three bits set to “1” and their fourth bit set to “0”. Class D addresses are 32-bit network addresses, meaning that all the values within the range of 224.0.0.0 – 239.255.255.255 are used to uniquely identify multicast groups. There are no host addresses within the Class D address space, since all the hosts within a group share the group’s IP address for receiver purposes. Example for a Class D IP address: 227.21.6.173
Class E networks are defined by having the first four network address bits as 1. That encompasses addresses from 240.0.0.0 to 255.255.255.255. While this class is reserved, its usage was never defined. As a result, most network implementations discard these addresses as illegal or undefined. The exception is 255.255.255.255, which is used as a broadcast address. Example for a Class D IP address: 243.164.89.28 Overview: IP address classes and bit-wise representations Class A 0. 0. 0. 0 = 00000000.00000000.00000000.00000000 127.255.255.255 = 01111111.11111111.11111111.11111111 0nnnnnnn.HHHHHHHH.HHHHHHHH.HHHHHHHH Class B 128. 0. 0. 0 = 10000000.00000000.00000000.00000000 191.255.255.255 = 10111111.11111111.11111111.11111111 10nnnnnn.nnnnnnnn.HHHHHHHH.HHHHHHHH Class C 192. 0. 0. 0 = 11000000.00000000.00000000.00000000 223.255.255.255 = 11011111.11111111.11111111.11111111 110nnnnn.nnnnnnnn.nnnnnnnn.HHHHHHHH Class D 224. 0. 0. 0 = 11100000.00000000.00000000.00000000 239.255.255.255 = 11101111.11111111.11111111.11111111 1110XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX Class E 240. 0. 0. 0 = 11110000.00000000.00000000.00000000 255.255.255.255 = 11111111.11111111.11111111.11111111 1111XXXX.XXXXXXXX.XXXXXXXX.XXXXXXXX Private addressesWithin the address space, certain networks are reserved for private networks. Packets from these networks are not routed across the public internet. This provides a way for private networks to use internal IP addresses without interfering with other networks. The private networks are 10.0.0.1 - 10.255.255.255 Special addressesCertain IPv4 addresses are set aside for specific uses: 127.0.0.0Loopback address (the host’s own interface)224.0.0.0IP Multicast255.255.255.255Broadcast (sent to all interfaces on network) IPv4 address exhaustionThe original IPv4 specification was designed for the DARPA network that would eventually become the internet. Originally a test network, no one contemplated how many addresses might be needed in the future. At the time, the 232 addresses (4.3 billion) were certainly considered sufficient. However, over time, it became apparent that as currently implemented, the IPv4 address space would not be big enough for a worldwide internet with numerous connected devices per person. The last top-level address blocks were allocated in 2011. Which of the following is the best description of an IP address?Which of the following is the best description of an IP address? An IP address is a unique number that identifies an Internet-connected device.
Which of the following is found in a routing table?A basic routing table includes the following information: Destination: The IP address of the packet's final destination. Next hop: The IP address to which the packet is forwarded. Interface: The outgoing network interface the device should use when forwarding the packet to the next hop or final destination.
Which of these addresses identify a computer on the network?An IP address identifies a device on the global internet, acting as the device's logical address to identify that network connection.
Which of these is a requirement for a computing device to access the Internet?There are three ingredients needed to access the Internet from a laptop or desktop computer: (1) an ISP, (2) a modem and (3) a Web browser.
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