Basic CCNA interview questions

10/23/2014 Basic CCNA Interview Questions AND Answers ~ Sysnet Notes
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Basic CCNA Interview Questions AND
Answers
by Shabeer ibm
What is Routing?
Routing is the process of selecting best paths in a network and forward data from
source to destination through it. Routing is usually performed by a dedicated device
called a router.
What is Protocol?
A 'protocol' is a set of invisible computer rules that enable two devices to connect
and transmit data to one another. Protocols determine how data are transmitted
between computing devices and over networks.
Explain difference between Router, Switch and Hub?
Hubs, switches, and routers are all computer networking devices with varying
capabilities. Let's look in detail
Hub
A hub is typically the least expensive, least intelligent, and least complicated of the
three. Its job is very simple – anything that comes in one port is sent out to the
others. Hub has single collision domain and single broadcast domain
Switch
Switch is a device that filters and forwards packets between LAN segments. Switches
operate at the data link layer (layer 2) and sometimes the network layer (layer 3) of
the OSI Reference Model and therefore support any packet protocol. Switches have
multiple collision domains and have a single broadcast domain
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Router
Router is a device that forwards data packets along networks. A router is connected
to at least two networks, commonly two LANs or WANs or a LAN and its ISP's
network. Routers won't forward broadcast. If a router is present in a network, we
may have at least TWO broadcast domains.
Explain broadcast and collision domain?
A broadcast domain is a logical division of a computer network, in which all nodes
can reach each other by broadcast at the data link layer.
A collision domain is a section of a network where data packets can collide
with one another when being sent on a shared medium or through repeaters
What is the size of IP Address?
32 bit for IPv4 and 128 bit for IPv6
IEEE standard for wireless networking?
IEEE 802.11
What is the range of class A address?
Class A Range from 1.0.0.1 to 126.255.255.254 and Supports 16 million hosts on each
of 127 networks.
What is the range of class B address?
Class B range from 128.1.0.1 to 191.255.255.254 and Supports 65,000 hosts on each of
16,000 networks.
What is the range of class C address?
Class C range is from 192.0.1.1 to 223.255.254.254 and Supports 254 hosts on each of
2 million networks.
What is PoE (Power over Ethernet)?
Power over Ethernet or PoE describes the technology which pass electrical power
along with data on Ethernet cabling. This allows a single cable to provide both data
connection and electrical power to devices such as wireless access points or IP
cameras.
What is a peer-peer process?
A peer-to-peer (P2P) network is a type of decentralized and distributed network
architecture in which individual nodes in the network (called "peers") act as both
suppliers and consumers of resources. There will be no centralized system we

usually seen like Client server model. Simply in p2p, network devices act as both
client and server
What is ping? Why you use ping?
Ping [Packet Internet Groper PING] a computer network tool used to test whether a
particular host is reachable across an IP network
What is the difference between tracert and traceroute
Both Tracert and traceroute commands do similar purpose. On a router or switch
you would use the command traceroute and on a pc you would use tracert .
What is Round Trip Time?
Round-trip time (RTT), also called round-trip delay, is the time required for a packet
to travel from a specific source to a specific destination and back again.Source is the
computer sending the packet and the destination is a remote computer or system
that receives the packet and retransmits it. A user can determine the RTT to and
from an IP address by pinging that address
Define the terms Unicast, Multicast and Broadcast and Anycast?
Unicast – One to One communication Eg: http
Multicast – One to a group Communication Eg: SLP
Broadcasting – One to All communication Eg: ARP
Anycast – One to nearest Communication Eg : 6to4
Where do we use cross and standard cable?
To connect same group device use Cross Cable
To connect different group device use Straight Cable
For Example:
To connect one PC to another PC use Cross Cable
To connect one comp to switch OR one switch to router use straight cable
What are the differences between static ip addressing and dynamic ip
addressing?
Dynamic IP addresses can change each time you connect to the Internet, while static
IP addresses are reserved for you statically and don't change over time. In short,
Dynamic IP addresses are provided by DHCP server and static IP addresses are given
manually
Difference between CSMA/CD and CSMA/CA?

Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is a media
access control method used in local area networking using early Ethernet technology
to overcome collision when it happened while Carrier sense multiple access with
collision avoidance (CSMA/CA) is used in wireless network to avoid collision
What is DHCP scope?
A Dynamic Host Configuration Protocol (DHCP) scope is the consecutive range of
possible IP addresses that the DHCP server can lease to clients on a subnet.
What is Checksum?
A simple error-detection scheme in which each transmitted message is accompanied
by a numerical value based on the number of set bits in the message. The receiving
station then applies the same formula to the message and checks to make sure the
accompanying numerical value is the same. If not, the receiver can assume that the
message has been garbled.
What is Redundancy?
Network redundancy is a method which provide a back up for the primary device
or route and thereby ensuring network will be available even the primary device or
route become failed or unavailable
What are the different memories used in a CISCO router?
ROM
ROM is read-only memory available on a router's processor board. The initial
bootstrap software that runs on a Cisco router is usually stored in ROM. ROM also
maintains instructions for Power-on Self Test (POST) diagnostics.
Flash Memory
Flash memory is an Electronically Erasable and Re-Programmable memory chip. The
Flash memory contains the full Operating System Image (IOS, Internetwork
Operating System).Flash memory retains content when router is powered down or
restarted.
RAM
RAM is very fast memory that loses its information when the router is shutdown or
restarted. On a router, RAM is used to hold running Cisco IOS Operating System, IOS
system tables and buffers RAM is also used to store routing tables,RAM Provides
temporary memory for the router configuration file of the router while the router is
powered on.

RAM Stores running Cisco IOS Operating System, Active program and operating
system instructions, the Running Configuration File, ARP (Address Resolution
Protocol) cache, routing tables and buffered IP Packets.
NVRAM (Non-volatile Random Access Memory)
NVRAM is used to store the Startup Configuration File. This is the configuration file
that IOS reads when the router boots up. It is extremely fast memory and retains its
content when the router is restarted.
What are the different types of passwords used in securing a CISCO router?
Here are the five passwords you can set on a Cisco router:
· Console
· Aux
· VTY
· Enable password
· Enable Secret
What is the use of "Service Password Encryption"?
"Service Password Encryption" command allows you to encrypt all
passwords(including clear text) on your router so they cannot be viewed from your
running-config
Define and explain the five conversion steps of data encapsulation.
Data encapsulation is a process that makes use of the layered model concept in that
each layer depends on the layer above and below relative to OSI. The lower layer
uses encapsulation to put the data from the upper layer into its own encapsulated
data field i.e., the information in a protocol is wrapped, or contained, in the data
section of another protocol.
In the process of encapsulation, header information is added to the data from the
above layer.
The five steps of conversion are
Step Action Layers Involved Keyword
Step 1 Alphanumeric input
from user converted
into Data
Application/Presentation/Session DATA
Step 2 Data converted into
segments
Transport SEGMENTS

Step 3 Segments converted
into Packets or
Datagrams and
Network Header is
added
Network PACKETS
Step 4 Packets or Datagrams
are built into Frames
Data Link FRAMES
Step 5 Frames are
converted into bits(
1s and 0s) for
transmission
Physical BITS
In configuring a router, what command must be used if you want to delete the
configuration data that is stored in the NVRAM?
#erase startup-config
Which command is used to copy the configuration from RAM to NVRAM
#Copy running-config startup-config
Differentiate Logical Topology from Physical Topology?
Physical topology is the network what we can see and Logical topology is the
network which data packets are send from source to destination
What is AS (Autonomous System)?
An autonomous system (AS) can be said as either a single network or a group of
networks that is controlled by a common network administrator (or group of
administrators) on behalf of a single administrative entity (such as a university, a
business enterprise, or a business division). An autonomous system is also
sometimes referred to as a routing domain. An autonomous system is assigned a
globally unique number, sometimes called an Autonomous System Number (ASN).
What is the difference between Private IP and Public IP?
Public IP is used across internet and Private IPs are used within the local LAN
Explain different cable types?
Straight cable – To connect different group devices (Switch – Router)
Cross Cable - To connect same group device (PC –PC, Switch –Switch)
Rollover cable – To connect Console port to Computer

How does RIP differ from EIGRP?
The major difference between both is that EIGRP is Cisco propriety and RIP is
open standard
Some internal differences between them are:
· AD value of Rip is 120 and AD value for EIGRP is 90 internal / 170
external.
· RIP uses Bellmen ford algorithm to calculate the path while Eigrp use
Dual method to calculate the routes paths
· Maximum hop count for RIP is 15 that is after 15 counts the packet is
dropped while that of EIGRP is 100 by default and upto 255 by configuration.
· RIP(ver 1) is classfull protocol where as EIGRP is classless protocol
· In RIP full routing table exchanged, but in EIGRP missing routes are
exchanged
· For RIP protocol, hello timers every 30 seconds but in EIGRP hello timer
every 5 seconds
· RIP v1 sends updates as broadcast while EIGRP send updates as Multicast
· EIGRP uses an Autonomous number to determine which domain it
belongs to which is not the case with RIP protocols.
· RIP is mostly used for smaller networks which EIGRP is used for larger
networks.
· RIP is a distance vector routing protocol while EIGRP is an hybrid routing
protocol.
· RIP sends full update whenever network change occurs whereas EIGRP
sends triggered updates
Differentiate User Mode from Privileged Mode
Privileged mode has access to the entire router or switch configuration. User EXEC
mode only has limited options. Specifically, to do any configuration changes, you
need to enter privileged mode first.User EXEC mode is used mainly for running show
commands and to collect details
What is 100BaseFX?
100BaseFX is a version of Fast Ethernet that is often used for wiring campus
backbones.
Differentiate full-duplex from half-duplex?
Full-duplex means that communication can occur in both directions at the same

time. Half-duplex means communication can only occur in one direction at a time
What does the "show protocol" display?
To display the configured protocols, use the show protocols command in user
EXEC or privileged EXEC mode.
#show protocols [interface-name interface-number]
If you find any mistake in this post feel free to write to shabeeribm@gmail.com
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