IPv4 and IPv6

block size

The number of IP addresses in a subnet, including the subnet's address and the subnet's directed broadcast address.

variable-length subnet masking (VLSM)

The process of assigning various subnetwork IDs in the network to issue the appropriate number of IP addresses.

subnet mask

A 32-bit value in (IPv4) that indicates what portion of the IP address is the network ID versus what portion is the host ID.

classful mask

A classful mask is the default subnet applied to Class A, B, and C IPv4 networks. Specifically, Class A networks have a classful mask of 255.0.0.0, Class B networks have a classful mask of 255.255.0.0, and Class C networks have a classful mask of 255.255.255.0.

octet

A grouping of 8 bits. An IPv4 address consists of 4 octets( that is, a total of 32 bits.)

Bootstrap Protocol (BOOTP)

A legacy broadcast-based protocol used by networked devices to obtain IP address information.

link-local IP address

A link-local IP address is a nonroutable IP address usable only on a local subnet.

loopback

A loopback interface on a network device is a logical (virtual) interface that is often used for testing purposes.

Extended Unique Identifier-64(EUI-64)

A method in IPv6 to calculate a unique host address portion for a node.

prefix notation

A method of indicating how many bits are in a subnet mask. For example, /24 is a prefix notation for a 24-bit subnet mask. Prefix notation is also known as slash notation.

dotted-decimal notation

A method of writing an IPv4 address or subnet mask, where groups of 8 bits(called octets) are separated by periods.

multicast

A multicast communication flow is one-to-many flow.

Zeroconf

A technology that performs 3 basic functions: assigning link-local IP addresses, resolving computer names to IP addresses, and locating network services.

borrowed bits

Bits added to a classful subnet mask.

router advertisement

Routers advertise their presence together with various link and Internet parameters, either periodically or in response to a Router Solicitation message.

classless interdomain routing (CIDR)

Shortens a classful subnet by removing right-justified 1s from a classful mask. As a result, CIDR allows contiguous classful networks to be aggregated. This process is sometimes called route aggregation.

private IP address

Specific Class A,B, and C networks have been designed for private use. Although these networks are routable (with the exception of the 169.254.0.0 - 169.254.255.255 address range), within the organization, service providers do not route these private networks over the public internet.

default gateway

The IP address of a router(or multilayer switch) to which a networked device sends traffic destined for a subnet other than the device's local subnet.

Dynamic Host Configuration Protocol (DHCP) Version 6

The IPv6 version of DHCP.

dual stack

The ability of a network interface to run multiple protocols, such as IP and IPv6.

unicast

A unicast communication flow is one-to-one flow.

Automatic Private IP Addressing (APIPA)

Allows a networked device to self-assign an IP address from the 169.254.0.0/16 network. Note that this address is only usable on the device's local subnet(meaning that the IP address in not routable).

anycast

An anycast communication flow is a one-to-neareset(from the perspective of a router's routing table) flow.

Neighbor discovery

Any process whereby network elements can discover each other on the network. In the case of EIGRP, hello packets are used, for example.

Dynamic Host Configuration Protocol (DHCP)

Dynamically assigns IP address information (ex: IP address, subnet mask, DNS server's IP address, and default gateway's IP address) to network devices.

IPv6 characteristics

IPv6 offers a simplified header using 5 fields. IPv6 offers a four time increase in the number of IP addresses than IPv4. IPv6 offers no fragmentation. IPv6 has 3 types of data flows: unicast, multicast, and anycast. IPv6 offers no broadcasts.

tunneling

Transmitting traffic with additional encapsulation.