Syngress - Eleventh Hour Network+ Exam N10-004 Study Guide (11 ...

Windows Tools 157
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■ The type of signal transmission used
■ The cable type
■ The actual layout or path of the network wiring
■ The voltage and electrical signals being used by the network cabling
■ The following physical devices function at the physical layer of the OSI
model: network cabling, network interface cards, active and passive hubs,
and repeaters.
The data link layer The data link layer is responsible for taking the information
from the physical layer and organizing it into frames. The functions
of the data link layer include the following:
■ Error checking and error-free delivery of data frames
■ Maintaining the reliability of the communications between two computers
■ The two types of devices that function at the data link layer of the OSI
model are switches and bridges.
The network layer The network layer takes the frames it receives from the
data link layer and organizes them into packets. Functions of the network
layer include the following:
■ Physical media access control (MAC) addresses are translated into
Internet Protocol (IP) addresses.
■ Routers exist at this layer.
■ Tools to check connectivity that function at the network layer include:
ping, tracert, traceroute, and pathping.
The transport layer The transport layer is where network packets are even
further differentiated by the port number. Functions of the transport layer
include the following:
■ Packets are differentiated by the Transmission Control Protocol (TCP) or
User Datagram Protocol (UDP) port number they include.
■ Firewalls and proxy servers will often function at the transport layer to
filter traffic.
WINDOWS TOOLS
The most common Windows tools that you should be aware of include the
following:
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Ping Uses Internet Control Message Protocol (ICMP) echo messages to
communicate with other computers. It is used to test basic TCP/IP connectivity
between two computers, using either hostname or IP address. Some
of the available command-line switches include ping −t, which will ping a
specified host continuously until you stop it by typing Ctrl + C, and ping
−a, which resolves IP addresses to hostnames.
Nslookup Allows you to test and query the records stored in your domain
naming service (DNS) server. Functions in two modes: command mode to
perform a single query, or in interactive mode to perform multiple queries.
Tracert Allows you to trace the path that a network packet will take from one
host to another. You can use tracert to determine whether one of the routers