Top Networking Questions and Answers
Top Networking Questions and Answers
Top Networking Questions and Answers
This term comes from the OSI Network management model.It is a kind
of virtual database used to manage the devices in a network.It consists
of record the of network entities( e.g. routers,switches) in form of
objects.The database is hierarchical (tree structured) and entries are
addressed through object identifiers.
7. What is REX?
The Mount protocol returns a file handle and the name of the file
system in which a requested file resides. The message is sent to the
client from the server after reception of a client's request.
15. What are the advantages and disadvantages of the three types of
routing tables?
The three types of routing tables are fixed, dynamic, and fixed central.
The fixed table must be manually modified every time there is a
change. A dynamic table changes its information based on network
traffic, reducing the amount of manual maintenance. A fixed central
table lets a manager modify only one table, which is then read by other
devices. The fixed central table reduces the need to update each
machine's table, as with the fixed table. Usually a dynamic table
causes the fewest problems for a network administrator, although the
table's contents can change without the administrator being aware of
the change.
It is using a router to answer ARP requests. This will be done when the
originating host believes that a destination is local, when in fact is lies
beyond router .
20. What is OSPF?
It is an Internet routing protocol that scales well, can route traffic along
multiple paths, and uses knowledge of an Internet's topology to make
accurate routing decisions
The most common two letter combinations are called as digrams. e.g.
th, in, er, re and an. The most common three letter combinations are
called as trigrams. e.g. the, ing, and, and ion.
When hierarchical routing is used, the routers are divided into what we
call regions, with each router knowing all the details about how to route
packets to destinations within its own region, but knowing nothing
about the internal structure of other regions.
One of two sublayers of the data link layer of OSI reference model, as
defined by the IEEE 802 standard. This sublayer is responsible for
maintaining the link between computers when they are sending data
across the physical network connection.
40. Why should you care about the OSI Reference Model?
41. What is the difference between routable and non- routable protocols?
Routable protocols can work with a router and can be used to build large
networks. Non-Routable protocols are designed to work on small, local
networks and cannot be used with a router
42. What is MAU?
In a Ethernet network, between any two points on the network, there can
be no more than five network segments or four repeaters, and of those
five segments only three of segments can be populated.
44. What is the difference between TFTP and FTP application layer
protocols?
The Trivial File Transfer Protocol (TFTP) allows a local host to obtain
files from a remote host but does not provide reliability or security. It
uses the fundamental packet delivery services offered by UDP.
46. What is the minimum and maximum length of the header in the TCP
segment and IP datagram?
The header should have a minimum length of 20 bytes and can have a
maximum length of 60 bytes.
49. What are the data units at different layers of the TCP / IP protocol
suite?
The data unit created at the application layer is called a message, at the
transport layer the data unit created is called either a segment or an
user datagram, at the network layer the data unit created is called the
datagram, at the data link layer the datagram is encapsulated in to a
frame and finally transmitted as signals along the transmission media.
Every line has an upper limit and a lower limit on the frequency of
signals it can carry. This limited range is called the bandwidth.
52. Difference between bit rate and baud rate?
Bit rate is the number of bits transmitted during one second whereas
baud rate refers to the number of signal units per second that are
required to represent those bits.
baud rate = bit rate / N
where N is no-of-bits represented by each signal shift.
Sap stands for Systems Applications & Products. Its basically an ERP
(Enterprise resource and planning) software. Its basically a package that
integrates all modules of a company like Finance, accounting, Sales &
Distribution, Material management, HR etc into one.
Hybrid devices that combine the features of both bridges and routers.
A gateway operates at the upper levels of the OSI model and translates
information between two completely different network architectures or
data formats.
Repeater:
Also called a regenerator, it is an electronic device that operates only at
physical layer. It receives the signal in the network before it becomes
weak, regenerates the original bit pattern and puts the refreshed copy
back in to the link.
Bridges:
These operate both in the physical and data link layers of LANs of same
type. They divide a larger network in to smaller segments. They contain
logic that allow them to keep the traffic for each segment separate and
thus are repeaters that relay a frame only the side of the segment
containing the intended recipent and control congestion.
Routers:
They relay packets among multiple interconnected networks (i.e. LANs
of different type). They operate in the physical, data link and network
layers. They contain software that enable them to determine which of
the several possible paths is the best for a particular transmission.
Gateways: They relay packets among networks that have different
protocols (e.g. between a LAN and a WAN). They accept a packet
formatted for one protocol and convert it to a packet formatted for
another protocol before forwarding it. They operate in all seven layers of
the OSI model.
When the computers on the network simply listen and receive the signal,
they are referred to as passive because they don’t amplify the signal in
any way. Example for passive topology - linear bus.
70. What are the important topologies for networks?
BUS topology:
In this each computer is directly connected to primary network cable in a
single line.
Advantages:
Inexpensive, easy to install, simple to understand, easy to extend.
STAR topology:
In this all computers are connected using a central hub.
Advantages:
Can be inexpensive, easy to install and reconfigure and easy to trouble
shoot physical problems.
RING topology:
In this all computers are connected in loop.
Advantages:
All computers have equal access to network media, installation can be
simple, and signal does not degrade as much as in other topologies
because each computer regenerates it.
Server-based network.
Peer-to-peer network.
The data unit in the LLC level is called the protocol data unit (PDU). The
PDU contains of four fields a destination service access point (DSAP), a
source service access point (SSAP), a control field and an information
field. DSAP, SSAP are addresses used by the LLC to identify the
protocol stacks on the receiving and sending machines that are
generating and using the data. The control field specifies whether the
PDU frame is a information frame (I - frame) or a supervisory frame (S -
frame) or a unnumbered frame (U - frame).
(i) Simplex
(ii) Half-duplex
(iii) Full-duplex.
Signals are usually transmitted over some transmission media that are
broadly classified in to two categories:-
Guided Media:
These are those that provide a conduit from one device to another that
include twisted-pair, coaxial cable and fiber-optic cable. A signal
traveling along any of these media is directed and is contained by the
physical limits of the medium. Twisted-pair and coaxial cable use
metallic that accept and transport signals in the form of electrical
current. Optical fiber is a glass or plastic cable that accepts and
transports signals in the form of light.
Unguided Media:
This is the wireless media that transport electromagnetic waves without
using a physical conductor. Signals are broadcast either through air.
This is done through radio communication, satellite communication and
cellular telephony.
(i) Broadcast
(ii) point-to-point.
Advantage
2. If you move your client machine to a different subnet, the client will
send out its discover message at boot time and work as usual.
However, when you first boot up there you will not be able to get back
the IP address you had at your previous location regardless of how
little time has passed.
Disadvantage
Your machine name does not change when you get a new IP address.
The DNS (Domain Name System) name is associated with your IP
address and therefore does change. This only presents a problem if
other clients try to access your machine by its DNS name.
84. What is the difference between POP3 and IMAP Mail Server?
3. Click Yes to copy the data from the server to your new Offline Folder
file (.ost).
86. What the difference between DNS and WINS?
Because the majority of networks use DNS these days, Windows 2000
and 2003 have migrated away from WINS and use DNS mainly.
While both services do identical jobs, that is, translate domains and
hostnames into IP addresses, DNS has become the number one
standard for name resolution and it surely won't change for a long time!
87. How can we create VPN to connect to branch office of the same office.
what would be the preliminary requirement?
88. Why should we care about the OSI Reference Model ? What is the
main purpose for creating this osi model? why it is a layered model?
Software in the user's computer that can access the mail servers in a
local or remote network. Also known as an "e-mail client," "mail client,"
"mail program," and "mail reader," it provides the ability to send and
receive e-mail messages and file attachments.
98. Name any field of IP header that can prevent a packet to loop
infinitely?
• Total Length
• Header Length
• More Fragments Flag
• Fragment Offset
• Header Checksum
99. Under what situations a packet can go into infinite loop in a network?
The synchronization requires each side to send its own initial sequence
number and to receive a confirmation of it in acknowledgement (ACK)
from the other side. Each side must also receive the other side's initial
sequence number and send a confirming ACK. This exchange is called
the three-way handshake