Access Control List: Plays a large role in network security. Defines the types of packets that
should be routed and which should be discarded.
Address Resolution: The process of determining the lower-layer address from a higher layer
address. This means turning the application layer address/server name of the destination into
a network layer address into a data link layer address.
Two Types: Server Name Resolution and Data Link Layer Address Resolution.
Address Resolution Protocol: The network layer protocol standard for data link layer
address resolution requests. Looks at IP address and asks the sender to send the data link
layer address. Formats broadcast messages.
Addressing: Used to direct messages from source to destination. A portion of an IP address
represents the network and the rest identifies the hosT.
Application layer address: Also known as a server name. Application software that uses
Internet addresses. Whenever a user types in an Internet address into a Web browser, the
request is passed to the network layer as part of an application layer packet formatted using
the HTTP protocol.
Autonomous systems: Is a network operated by one organization like IBM. Or an
organization that runs one part of the Internet.
Auxiliary port: A port that allows an administrator to log in via a direct, non-network
connection. Rarely used today.
Border Gateway Protocol[BGP]: A network layer standard exterior protocol used to
exchange route information between routers using dynamic, decentralized routing. Used for
large sections of the Internet (autonomous systems).
Border router: Part of each autonomous system that connects it to the adjacent autonomous
systems and exchanges route information via BGP.
Broadcast message: Is received and processed by all computers on the same LAN (which is
usually designed to match the IP subnet).
Centralized routing: All routing decisions are made by one central computer or router. Is
used often in host based networks.
Cisco IOS: IOS= Internetwork Operating System. The operating system that is used in about
90% of routers. The IOS uses a command line interface.
Classless advertizing: Also called slash notation. A slash used to indicate the address range.
Example: 188.8.131.52/24 means the first 24 bits (3 bytes) are fixed and the company can
allocate the last byte (8 bits).
Connectionless messsaging: Means each packet is treated separately and makes its own way
through the network.
Connection-oriented messaging: Sets up a TCP connection (also called session) between the
sender and receiver. Uses the three way handshake (SYN, SYN-ACK,SYN)
Console port: Also called management port. Configures the router. Uses a console cable and
computer with a serial line connected to the router.
Data link layer address: Also known as the physical address/MAC address. Is on the
network interface card. Are needed only on multipoint circuits (which have more than one
computer on them). Ex: 00-0C-00-F5-03-5A
Designated router: A special router that manages routing information for networks that use
OSPF (Open Shortest Path First-an interior routing protocol).
Destination port address: The address of the receiver of a message in regards to using
Distance vector dynamic: The router counts the number of hops along a route. A hop is one
Domain Name Service [DNS]: Are name servers that perform IP address resolution.
Dynamic addressing: A server is designated to supply a network layer address to a computer
each time the computer connects to the network.
Dynamic Host Configuration Protocol[DHCP]: Is the most standard way of doing dynamic
addressing. A network-layer protocol standard used to supply TCP/IP address information
using dynamic address assignments.
Dynamic routing: Also called adaptive routing. Lets all computers on the network make
their own routing decisions. Used when there are multiple routes through a network.
1st: It requires more processing by each computer or router in the network than centralized or
2nd: The transmission of routing information wastes network capacity.
Enhanced Interior Gateway Routing Protocol[EIGRP]: It's a dynamic hybrid (has features of
both distance vector protocols and link state protocols) interior routing protocol made by
Cisco and is used in organizations. Records info on a route's transmission, capacity, delay,
reliability, and load.
It is unique in that it lets computers or routers store their own routing table as well as its
neighbors routing tables.
Exterior routing protocol: Protocols used between autonomous systems. Are designed to be
selective in the information it provides-gives information about only the preferred or best
routes. Gateway: A device that connects two different networks. Allows networks of different
vendors to communicate by translating