CCNA Academy Chapter 6

A) source b) destination ***These addresses are used in the data network as binary patterns. Inside the devices, digital logic is applied for their interpretation. For us in the human network, a string of 32 bits is difficult to interpret and even more difficult to remember. Therefore, we represent IPv4 addresses using dotted decimal format.

Binary patterns representing IPv4 addresses are expressed as dotted decimals by separating each byte of the binary pattern, called an octet, with a dot. It is called an octet because each decimal number represents one byte or 8 bits. For example, the address: 10101100000100000000010000010100 is expressed in dotted decimal as:

A) identical bit ***Although all 32 bits define the IPv4 host address, we have a variable number of bits that are called the host portion of the address. The number of bits used in this host portion determines the number of hosts that we can have within the network.

A) binary ***Data represented in binary may represent many different forms of data to the human network. In this discussion, we refer to binary as it relates to IPv4 addressing. This means that we look at each byte (octet) as a decimal number in the range of 0 to 255.

Learning to convert binary to decimal requires an understanding of the mathematical basis of a numbering system called positional notation. Positional notation means that a digit represents different values depending on the position it occupies. More specifically, the value that a digit represents is that value multiplied by the power of the base, or radix, represented by the position the digit occupies. 1 1 1 1 1 1 1 1 128 64 32 16 8 4 2 1 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255

Is converted to: 172.16.4.20 Keep these steps in mind: Divide the 32 bits into 4 octets.
Convert each octet to decimal.
Add a "dot" between each decimal.

Network address - The address by which we refer to the network Broadcast address - A special address used to send data to all hosts in the network Host addresses - The addresses assigned to the end devices in the network

The network address is a standard way to refer to a network. For example, we could refer to the network shown in the figure as "the 10.0.0.0 network." This is a much more convenient and descriptive way to refer to the network than using a term like "the first network." All hosts in the 10.0.0.0 network will have the same network bits.

The IPv4 broadcast address is a special address for each network that allows communication to all the hosts in that network. To send data to all hosts in a network, a host can send a single packet that is addressed to the broadcast address of the network.

As described previously, every end device requires a unique address to deliver a packet to that host. In IPv4 addresses, we assign the values between the network address and the broadcast address to the devices in that network.

When we express an IPv4 network address, we add a prefix length to the network address. The prefix length is the number of bits in the address that gives us the network portion. For example, in 172.16.4.0 /24, the /24 is the prefix length - it tells us that the first 24 bits are the network address. This leaves the remaining 8 bits, the last octet, as the host portion.

A) 32 bits

Unicast - the process of sending a packet from one host to an individual host Broadcast - the process of sending a packet from one host to all hosts in the network Multicast - the process of sending a packet from one host to a selected group of hosts

Unicast communication is used for the normal host-to-host communication in both a client/server and a peer-to-peer network. Unicast packets use the host address of the destination device as the destination address and can be routed through an internetwork. Broadcast and multicast, however, use special addresses as the destination address. Using these special addresses, broadcasts are generally restricted to the local network. The scope of multicast traffic also may be limited to the local network or routed through an internetwork.
Note: In this course, all communications between devices is unicast communication unless otherwise noted.

Because broadcast traffic is used to send packets to all hosts in the network, a packet uses a special broadcast address. When a host receives a packet with the broadcast address as the destination, it processes the packet as it would a packet to its unicast address. Broadcast transmission is used for the location of special services/devices for which the address is not known or when a host needs to provide information to all the hosts on the network. Some examples for using broadcast transmission are: Mapping upper layer addresses to lower layer addresses
Requesting an address
Exchanging routing information by routing protocols
When a host needs information, the host sends a request, called a query, to the broadcast address. All hosts in the network receive and process this query. One or more of the hosts with the requested information will respond, typically using unicast. Similarly, when a host needs to send information to the