Certification: Network+ Certification is
offered by CompTIA. CompTIA recommends the aspirants to
pass A+ certification, but its is NOT a prerequisite.
Network+ exam topics include ISO OSI model, planning,
installing, and troubleshooting basic network
infrastructure. The candidate will be tested primarily on
Unix/Linux, Windows 9x, Windows NT, and Windows 2000
The sections that Network+ exam covers are given below
(subject to change):
||Media and Topologies
Protocols and Standards
Points to remember:
The 7 layers of OSI model are:
Application Layer: Application layer is responsible for
identifying and establishing the availability of desired
communication partner and verifying sufficient resources
exist for communication. Some of the important application
layer protocols are: WWW, SMTP, FTP, etc.
Presentation Layer: This layer is responsible for
presenting the data in standard formats. This layer is
responsible for data compression, decompression,
encryption, and decryption. Some Presentation Layer
standards are: JPEG, MPEG, MIDI, PICT, Quick Time, TIFF.
Session Layer: Session Layer is responsible for co-ordinating
communication between systems/nodes.
The following are some of the session layer
protocols and interfaces: a) Network File System (NFS),
SQL, RPC (Remote Procedure Call), X-Windows, ASP, DNA SCP.
Transport Layer: The Transport Layer is responsible for
multiplexing upper-layer applications, session
establishment, and tearing-down of virtual circuits. This
layer is responsible for flow control, to maintain data
Network Layer: There can be several paths to send a packet
from a given source to a destination. The primary
responsibility of Network layer is to send packets from
the source network to the destination network using a
pre-determined routing methods. Routers work at Network
Data Link Layer:
Link Layer is layer 2 of OSI reference model. This layer
is divided into two sub-layers:
Logical Link Control (LLC) sub-layer.
Media Access Control (MAC) sub-layer.
LLC sub-layer handles error control, flow control,
framing, and MAC sub-layer addressing.
MAC sub-layer is the lower of the two sub-layers of the
Data Link layer. MAC sub-layer handles access to shared
media, such a Token passing or Ethernet.
Layer: The actual flow of signals take place through
Physical layer. At Physical layer, the interface between
the DTE and DCE is determined. The following are some of
the standard interfaces are defined at Physical layer: EIA/TIA-232,
EIA/TIA-449,V.24,V.35,X.21,G.703,HSSI (High Speed Serial
Internetwork IP addressing:
IP addresses are written using decimal numbers separated
by decimal points. This is called dotted decimal notation
of expressing IP addresses.
different classes of IP addresses is as below:
Network address of all zeros means "This network or
Network address of all 1s means " all networks",
same as hexadecimal of all Fs.
Network number 127 is reserved for loop-back tests.
Host (Node) address
of all zeros mean "This Host (Node)".
Host (Node) address of all 1s mean "all Hosts (Nodes)
" on the specified network.
The range of numbers from 220.127.116.11 to 18.104.22.168 are
used for multicast packets. This is known as Class D
4. Subnetting is nothing but creating networks within a
network. Subnetting allows an organization with a single
IP address (Class A /ClassB /ClassC) to have multiple
subnetworks, thus allowing several physical networks
within the organization.
- Default subnet mask for Class A network: 255.0.0.0
- Default subnet mask for Class B network: 255.255.0.0
- Default subnet mask for Class C network: 255.255.255.0
127.0.0.1 is the local loop back address.
an internetwork, the number of distinct IPs' required are
each per client computer
each per server computer
each per router interface.
example, your network has 2 servers, 26 clients machines,
and 2 router interfaces the total number of IP addresses
required are 30.
directed broadcast should reach all Hosts on the intended
network (or subnet, if sub netted). For example, the
directed broadcast address for an IP network 22.214.171.124
with default subnet mask is 126.96.36.199. This is
arrived by putting all 1s for the host potion of the IP
Telnet, FTP, and TFTP:
is used for terminal emulation that runs programs
remotely. Telnet uses TCP/IP protocol.
requires a username and password to access.
(File Transfer Protocol) is a connection oriented
protocol. It uses TCP/IP for file transfer. Compare this
with TFTP (Trivial File Transfer Protocol) that uses UDP
(Connectionless protocol). SNMP uses UDP over IP. Tracert,
Ping use ICMP as their base protocol. FTP is used to
FTP and Telnet are client-server protocols. Note that
TCP/IP is a client server oriented protocol.
port numbers used by different programs are as below:
FTP : Port #21
SNMP: Port #161
is important to know that FTP, Telnet, SMTP use TCP;
whereas TFTP, SNMP use UDP.
is part of TCP/IP protocol suite. It allows you to monitor
and manage a network from a centralized place by using
SNMP Manager software. The systems or devices that provide
the responses are called agents (or MIBs). An SNMP agent
is any computer running SNMP agent software.
stands for Management Information Base. It is part of SNMP
agent database. A MIB records and stores information abut
the host it is running on. An SNMP manager can request and
collect information from an agent's MIB. Routers are
typical MIB agents. SNMP agent generates "trap"
messages that are then sent to an SNMP management console,
which is a trap destination.
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