ccna interview questions

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CCNA INTERVIEW QUESTIONS
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Which layer of the OSI model is responsible for
reliable connections? Answer The Transport layer
of the OSI model is responsible for reliable
connections. What is the difference between
acknowledgments and handshaking? Answer
Handshaking is used to negotiate the properties
of a connection that is being established.
Acknowledgments are used to tell the sender that
data has been successfully received by the
destination during the use of a connection. How
many VTP modes are there and what are
they? Answer Three Server, Client, and
Transparent What are the two types of Trunk
encapsulation protocols? Answer IEEE 802.1Q and
Ciscos ISL What are the four primary no
routable protocols? Answer SNA, NetBIOS, DEC
LAT, DEC MOP
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What is the difference between TCP and
UDP? Answer The primary difference between TCP
and UDP is that TCP is a connection oriented
protocol and UDP is a connection less
protocol. What is HSRP? Answer HSRP, or the Hot
Standby Routing Protocol, is a Cisco proprietary
protocol that brings routing functionality to end
devices that would otherwise not be capable of
taking advantage of redundant network
connections. HSRP enables a pair of Cisco routers
to work together to present the appearance of a
single virtual default-gateway to end devices on
a LAN segment. What is the difference between a
Public IP address and a Private IP
address? Answer Public address space is a unique
address that is assigned to a company. Private
address space is not recognized by the Internet
and can be used by anyone within their private
network. What does AAA stand for? Answer
Authentication, authorization, and accounting
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The H.323 protocol is used for what? Answer
H.323 is used for multi service (multimedia)
applications, usually in a Voice Over IP
environment. What type of routing protocol
maintains neighbors? Answer- Link State what is
the range of values for administrative
distance? Answer 0-255 Describe the difference
between uni cast, multi cast, and broadcast
traffic? Answer Unicast traffic flows from a
single source to a single destination MAC
address. Multicast traffic flows from a single
source MAC address to many destinations and uses
a functional MAC address. Broadcast traffic is
from a single source to all devices on the
Ethernet segment. This is specified by a
destination MAC address of all ones.
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What are the four different Ethernet
encapsulation types? Answer From the Cisco IPX
encapsulation command they are ARPA, NOVEL-ETHER,
SAP and SNAP What are the three main tasks of a
transparent bridge? Answer Learning, Forwarding,
Filtering What type of routing protocol is
EIGRP? Answer Hybrid While troubleshooting a
connectivity problem on the network, you issue
the ping command from your PC command prompt, but
the output shows request times out. At which
OSI layer is this problem associated
with? Answer The Network Layer What algorithm
does OSPF use to compute its route table? Answer
OSPF uses the shortest path first (SPF)
algorithm, which is also known as the Dijkstra
algorithm.
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What is a stub area? Answer A stub area is an
area that does not accept routing updates from
outside its autonomous system. What does the TTL
field of an IP packet header do? Answer The TTL
field indicates the maximum time that a packet
can be on the network. Each router that processes
this packet decrements the TTL value by 1. If the
value reaches zero, the packet is discarded from
the network. The purpose of this field is to
eliminate the possibility of a packet endlessly
traversing the network. What is the primary
purpose of a LAN? Answer The primary purpose of
a local-area network is to allow resource
sharing. The resources may be devices,
applications, or information. Examples of shared
resources are files, databases, e-mail, modems,
and printers. What is a protocol? Answer A
protocol is an agreed-upon set of rules. In data
communications, the rules usually govern a
procedure or a format.
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What is the purpose of a MAC protocol? Answer A
Media Access Control protocol defines how a given
LAN medium is shared, how LAN devices connected
to the medium are identified, and how frames
transmitted onto the medium are What is a
frame? Answer A frame is a digital envelope
that provides the information necessary for the
delivery of data across a data link. Typical
components of a frame are identifiers (addresses)
of the source and destination devices on the data
link, an indicator of the type of data enclosed
in the frame, anderor-checking information. What
feature is common to all frame types? Answer A
feature common to all frame types is a format for
identifying devices on the data link. What is a
MAC address or MAC identifier? Answer A Media
Access Control address or identifier is a means
by which individual devices connected to a data
link are uniquely identified for the purpose of
delivering data.
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Why is a MAC address not a true address? Answer
An address specifies a location. A MAC address is
not a true address because it is permanently
associated with the interface of a specific
device and moves whenever the device moves. A MAC
identifies the device, not the location of the
device. What are the three sources of signal
degradation on a data link? Answer The three
sources of signal degradation on a data link are
attenuation, interference, and distortion.
Attenuation is a function of the resistance of
the medium. Interference is a function of noise
entering the medium. Distortion is a function of
the reactive characteristics of the medium, which
react differently to different frequency
components of the signal. What is the purpose of
a repeater? Answer A repeater is a device that
extends the useful range of a physical medium by
reading a degraded signal and producing a clean
copy of the signal.
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What is the purpose of a bridge? Answer A bridge
is a device that increases the capacity of a LAN.
A bridge divides the data link into segments,
forwarding only traffic that is generated on one
segment and is destined for another segment. By
controlling and limiting the traffic on a data
link, more devices may be attached to the
LAN. What makes a transparent bridge
transparent? Answer A transparent bridge
listens promiscuously on each of its ports.
That is, it examines all frames on all media to
which it is attached. It records the source MAC
identifiers of the frames, and the ports on which
it learns the identifiers, in a bridging table.
It can then refer to the table when deciding
whether to filter or forward a frame. The bridge
is transparent because it performs this learning
function independently of the devices that
originate the frames. The end devices themselves
have no knowledge of the bridge.
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Name three fundamental differences between LANs
and WANs? Answer Three fundamental differences
between local-area and wide-area networks
are LANs are limited to a small geographic
area, such as a single building or small
campus.WANs cover a large geographic area, from
citywide to worldwide. LANs usually consist
entirely of privately owned components. Some
components of a WAN, such as a packet switching
network or point-to-point serial links, are
usually leased from a service provider. A LAN
provides high bandwidth at a relatively cheap
price. The bandwidth across a WAN is
significantly more expensive. What is the
purpose of a broadcast MAC identifier? What is
the broadcast MAC identifier, in hex and in
binary? Answer A broadcast MAC identifier, when
used as the destination address of a frame,
signifies that the data is for all devices
attached to the data link. In binary, the
broadcast MAC identifier is all ones. In hex, it
is ffff.ffff.ffff.