Networking
concepts
- What are the two types of transmission technology available?
(i)
Broadcast and (ii) point-to-point
- What is subnet?
A
generic term for section of a large networks usually separated by a
bridge or router.
- Difference between the communication and transmission.
Transmission
is a physical movement of information and concern issues like bit
polarity, synchronisation, clock etc.
Communication
means the meaning full exchange of information between two
communication media.
- What are the possible ways of data exchange?
(i)
Simplex (ii) Half-duplex (iii) Full-duplex.
- What is SAP?
Series
of interface points that allow other computers to communicate with
the other layers of network protocol stack.
- What do you meant by "triple X" in Networks?
The
function of PAD (Packet Assembler Disassembler) is described in a
document known as X.3. The standard protocol has been defined between
the terminal and the PAD, called X.28; another standard protocol
exists between hte PAD and the network, called X.29. Together, these
three recommendations are often called "triple X"
- What is frame relay, in which layer it comes?
Frame relay is a packet switching technology. It will
operate in the data link layer.
- What is terminal emulation, in which layer it comes?
Telnet
is also called as terminal emulation. It belongs to application
layer.
- What is Beaconing?
The
process that allows a network to self-repair networks problems. The
stations on the network notify the other stations on the ring when
they are not receiving the transmissions. Beaconing is used in Token
ring and FDDI networks.
- What is redirector?
Redirector
is software that intercepts file or prints I/O requests and
translates them into network requests. This comes under presentation
layer.
- What is NETBIOS and NETBEUI?
NETBIOS
is a programming interface that allows I/O requests to be sent to and
received from a remote computer and it hides the networking hardware
from applications.
NETBEUI
is NetBIOS extended user interface. A transport protocol designed by
microsoft and IBM for the use on small subnets.
- What is RAID?
A
method for providing fault tolerance by using multiple hard disk
drives.
- What is passive topology?
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.
- What is Brouter?
Hybrid
devices that combine the features of both bridges and routers.
- What is cladding?
A
layer of a glass surrounding the center fiber of glass inside a
fiber-optic cable.
- What is point-to-point protocol
A
communications protocol used to connect computers to remote
networking services including Internet service providers.
- How Gateway is different from Routers?
A
gateway operates at the upper levels of the OSI model and translates
information between two completely different network architectures or
data formats
- What is attenuation?
The
degeneration of a signal over distance on a network cable is called
attenuation.
- What is MAC address?
The
address for a device as it is identified at the Media Access Control
(MAC) layer in the network architecture. MAC address is usually
stored in ROM on the network adapter card and is unique.
- 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.
- What is Bandwidth?
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.
- What are the types of Transmission media?
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.
b)
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.
- What is Project 802?
It
is a project started by IEEE to set standards to enable
intercommunication between equipment from a variety of manufacturers.
It is a way for specifying functions of the physical layer, the data
link layer and to some extent the network layer to allow for
interconnectivity of major LAN
protocols.
It
consists of the following:
- 802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.
- 802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.
- Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).
- 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.
- What is Protocol Data Unit?
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).
- What are the different type of networking / internetworking devices?
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.
- What is ICMP?
ICMP
is Internet Control Message Protocol, a network layer protocol of the
TCP/IP suite used by hosts and gateways to send notification of
datagram problems back to the sender. It uses the echo test / reply
to test whether a destination is reachable and responding. It also
handles both control and error messages.
- 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.
- What is difference between ARP and RARP?
The
address resolution protocol (ARP) is used to associate the 32 bit IP
address with the 48 bit physical address, used by a host or a router
to find the physical address of another host on its network by
sending a ARP query packet that includes the IP address of the
receiver.
The
reverse address resolution protocol (RARP) allows a host to discover
its Internet address when it knows only its physical address.
- 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.
- What is the range of addresses in the classes of internet addresses?
Class
A 0.0.0.0 - 127.255.255.255
Class
B 128.0.0.0 - 191.255.255.255
Class
C 192.0.0.0 - 223.255.255.255
Class
D 224.0.0.0 - 239.255.255.255
Class
E 240.0.0.0 - 247.255.255.255
- 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.
The File
Transfer Protocol (FTP) is the standard mechanism provided by TCP /
IP for copying a file from one host to another. It uses the services
offer by TCP and so is reliable and secure. It establishes two
connections (virtual circuits) between the hosts, one for data
transfer and another for control information.
- What are major types of networks and explain?
- Server-based network
- Peer-to-peer network
Peer-to-peer network, computers can act as both servers
sharing resources and as clients using the resources.
Server-based networks provide centralized control of
network resources and rely on server computers to provide security
and network administration
- 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.
- What is mesh network?
A network in which there are multiple network links
between computers to provide multiple paths for data to travel.
- What is difference between baseband and broadband transmission?
In a baseband transmission, the entire bandwidth of the
cable is consumed by a single signal. In broadband transmission,
signals are sent on multiple frequencies, allowing multiple signals
to be sent simultaneously.
- Explain 5-4-3 rule?
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.
- What MAU?
In token Ring , hub is called Multistation Access
Unit(MAU).
- 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
- Why should you care about the OSI Reference Model?
It provides a framework for discussing network
operations and design.
- What is logical link control?
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.
- What is virtual channel?
Virtual
channel is normally a connection from one source to one destination,
although multicast connections are also permitted. The other name for
virtual channel is virtual circuit.
- What is virtual path?
Along
any transmission path from a given source to a given destination, a
group of virtual circuits can be grouped together into what is called
path.
- What is packet filter?
Packet
filter is a standard router equipped with some extra functionality.
The extra functionality allows every incoming or outgoing packet to
be inspected. Packets meeting some criterion are forwarded normally.
Those that fail the test are dropped.
- What is traffic shaping?
One
of the main causes of congestion is that traffic is often busy. If
hosts could be made to transmit at a uniform rate, congestion would
be less common. Another open loop method to help manage congestion is
forcing the packet to be transmitted at a more predictable rate. This
is called traffic shaping.
- What is multicast routing?
Sending
a message to a group is called multicasting, and its routing
algorithm is called multicast routing.
- What is region?
When
hierarchical routing is used, the routers are divided into what we
will 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.
- What is silly window syndrome?
It
is a problem that can ruin TCP performance. This problem occurs when
data are passed to the sending TCP entity in large blocks, but an
interactive application on the receiving side reads 1 byte at a time.
- What are Digrams and Trigrams?
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.
- Expand IDEA.
IDEA
stands for International Data Encryption Algorithm.
- What is wide-mouth frog?
Wide-mouth
frog is the simplest known key distribution center (KDC)
authentication protocol.
- What is Mail Gateway?
It is a system that performs a protocol translation
between different electronic mail delivery protocols.
- What is IGP (Interior Gateway Protocol)?
It is any routing protocol used within an autonomous
system.
- What is EGP (Exterior Gateway Protocol)?
It is the protocol the routers in neighboring autonomous
systems use to identify the set of networks that can be reached
within or via each autonomous system.
- What is autonomous system?
It is a collection of routers under the control of a
single administrative authority and that uses a common Interior
Gateway Protocol.
- What is BGP (Border Gateway Protocol)?
It is a protocol used to advertise the set of networks
that can be reached with in an autonomous system. BGP enables this
information to be shared with the autonomous system. This is newer
than EGP (Exterior Gateway Protocol).
- What is Gateway-to-Gateway protocol?
It is a protocol formerly used to exchange routing
information between Internet core routers.
- What is NVT (Network Virtual Terminal)?
It is a set of rules defining a very simple virtual
terminal interaction. The NVT is used in the start of a Telnet
session.
- What is a Multi-homed Host?
It is a host that has a multiple network interfaces and
that requires multiple IP addresses is called as a Multi-homed Host.
- What is Kerberos?
It is an authentication service developed at the
Massachusetts Institute of Technology. Kerberos uses encryption to
prevent intruders from discovering passwords and gaining unauthorized
access to files.
- 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.
- What is Proxy ARP?
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.
- What is SLIP (Serial Line Interface Protocol)?
It is a very simple protocol used for transmission of IP
datagrams across a serial line.
- What is RIP (Routing Information Protocol)?
It is a simple protocol used to exchange information
between the routers.
- What is source route?
It is a sequence of IP addresses identifying the route a
datagram must follow. A source route may optionally be included in an
IP datagram header.
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