What is the use of kerberos protocol ?
Kerberos is a system of authentication developed at MIT as part of the Athena project. Kerberos uses encryption technology and a trusted third party, an arbitrator, to perform secure authentication on an open network. Specifically, Kerberos uses cryptographic tickets in order to avoid transmitting plaintext passwords over the wire. Kerberos was based upon the Needham-Schroeder protocol.
Kerberos is an authentication protocol which is used at the time of the user login.
The authentication is done in the Domain Controller where the user account is present.
In the other words “It is a request from the user to the DC to provide the services of the their own
private and also inter network.
what is difference beetween ISDN and ATM?
ISDN is an example of Circuite switching but ATM is Packet Switching or Cell switching.
Integrated Services refers to ISDN’s ability to deliver at minimum two simultaneous connections, in
any combination of data, voice, video, and fax, over a single line. Multiple devices can be attached to
the line, and used as needed. That means an ISDN line can take care of most people’s complete
communications needs at a much higher transmission rate, without forcing the purchase of multiple
analog phone lines.
Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer
protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header
information) fixed-sized cells. ATM provides data link layer services that run over Layer 1 links. This
differs from other technologies based on packet-switched networks (such as the Internet Protocol or
Ethernet), in which variable sized packets (known as frames when referencing layer 2) are used. ATM
is a connection-oriented technology, in which a logical connection is established between the two
endpoints before the actual data exchange begins.
What is meant by 2-Tier architecture?
In 2-tier Client/Server systems, the application logic is either burried inside the user interface on the
client or within the database on the server. Example: File servers and Database servers with stored
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 Subnetting? Why is it used?
Used in IP Networks to break up larger networks into smaller subnetworks. It is used to reduce
network traffic, Optimized network performance, and simplify management i.e. to identify and isolate
It is the process of dividing the single network into multiple multiple subnetting is known as
subnetting. Uses are
2.Maintaince & adminstration are simple
3.Restructing of network is simple.
What is attenuation?
The degeneration of a signal over distance on a network cable is called attenuation. Attenuation means loss of signal due to external interference or long distance.
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 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
ARP is used to determine the physical address(MAC Address) of the device only when its ip address is
known. ARP is also used to translate the IP address to Ethernet MAC address. Each device has a
physical address imprinted on the Network Interface Card(NIC).ARP used to associate an IP address
with the phycial address.
RARP is used to determine the IP address of the host only when the physical address (MAC Address)
is known. It’s useful when the computer is connected to the network for the first time.
What is meant by Symmentric Multiprocessing (SMP)?
It treats all processors as equal. Any processor can do the work of any other processor. Applications
are divided into threads that can run concurrently on any available processor. Any processor in the
pool can run the OS kernel and execute user-written threads.
What is meant by Asymmetric Multiprocessing (AMP)?
It imposses hierarchy and a division of labour among processors. Only one designated processor, the
master, controls (in a tightly coupled arrangement) slave processors dedicated to specific functions.
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 are the functions of the typical server program?
It waits for client-initiated requests. Executes many requests at the same time. Takes care of VIP
clients first. Initiates and runs background task activity. Keeps running. Grown bigger and faster.
What is the Differnece between Straight & Crossover Cables? & also describe their functions
Straight cable is used to connect different device like pc to Hub,Pc to switch,Router to Router. Cross
cable is used to connect similar device like PC to PC,Hub to Hub,Pc to Router.
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 deference between bootp and dhcp?
BOOTP supports a limited number of client configuration parameters called vendor extensions , while
DHCP supports a larger and extensible set of client configuration parameters called options.
BOOTP uses a two-phase bootstrap configuration process in which clients contact BOOTP servers to
perform address determination and boot file name selection, and clients contact Trivial File Transfer
Protocol (TFTP) servers to perform file transfer of their boot image. DHCP uses a single-phase boot
configuration process whereby a DHCP client negotiates with a DHCP server to determine its IP
address and obtain any other initial configuration details it needs for network operation.
BOOTP clients do not rebind or renew configuration with the BOOTP server except when the system
restarts, while DHCP clients do not require a system restart to rebind or renew configuration with the
DHCP server. Instead, clients automatically enter the Rebinding state at set timed intervals to renew
their leased address allocation with the DHCP server. This process occurs in the background and is
transparent to the user.
What are Triggers and Rules?
Triggers are special user defined actions usually in the form of stored procedures, that are
automatically invoked by the server based on data related events. It can perform complex actions
and can use the full power of procedural languages. A rule is a special type of trigger that is used to
perform simple checks on data.
What are the building blocks of Client/Server?
* The client
* The server and
In the TCP client-servel model, how does the three-way handshake work in opening connection?
The client first sends a packet with sequence “x” to the server. When the server receives this packet,
the server will send back another packet with sequence “y”, acknowledging the request of the client.
When the client receives the acknowledgement from the server, the client will then send an
acknowledge back to the server for acknowledging that sequence “y” has been received.
Client sends a request for connection.
Then both agrees upon the connection rules, eg how much data have to be send,connection mode
Then the server sends a ack that the connection has been stablished and is ready to transfer the
What are called Fat clients and Fat servers?
If the bulk of the application runs on the Client side, then it is Fat clients. It is used for decision
support and personal software.
If the bulk of the application runs on the Server side, then it is Fat servers. It tries to minimize
network interchanges by creating more abstract levels of services.
What is Client/Server?
Clients and Servers are separate logical entities that work together over a network to accomplish a
task. Many systems with very different architectures that are connected together are also called
Client/server describes the relationship between two computer programs in which one program, the
client, makes a service request from another program, the server, which fulfills the request.
What is a Database Server?
With a database server, the client passes SQL requests as messages to the database server. The
results of each SQL command are returned over the network. The server uses its own processing
power to find the request data instead of passing all the records back to the client and then getting it
find its own data. The result is a much more efficient use of distributed processing power. It is also
known as SQL engine.
What is Groupware server?
Groupware addresses the management of semi-structured information such as text, image, mail,
bulletin boards and the flow of work. These Client/Server systems have people in direct contact with
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
Gateway Uses NAT(Network Address Translation) to convert private IP address to Public IP
address and it also uses Port Address translation(PAT).
What is networking?
Networking is a technology where we can share data and resources available with one computer to n number of computers by using some extra hardware. Networking makes more than one computer to communicate.
What is OLTP?
In the transaction server, the client component usually includes GUI and the server components
usually consists of SQL transactions against a database. These applications are called OLTP
(Online Transaction Processing) OLTP Applications typically,Receive a fixed set of inputs from remote clients. Perform multiple pre-compiled SQL comments against a local database. Commit the work and Return a fixed set of results.
What is Brouter?
Hybrid devices that combine the features of both bridges and routers.It performs both switching at layer 2 and routing ant layer 3
What is supernetting? Why it is used?
Supernetting refers to increase host and reduce the subnet’s. It mean reduce the network bits and increase the host bits. We do use supernetting because when the PCs in the network increase where we need the more valid IP’s in the same network.
Supernetting is dividing the Subnet into different subnets each one of them has its particular required needs , such as Number of Networks and Number of Hosts.
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.
Explain the function of Transmission Control Block
A TCB is a complex data structure that contains a considerable amount of information about each connection. Short for trusted computing base. TCB refers to the totality of protection mechanisms
(hardware, firmware and software) that provide a secure computing environment. The TCB includes everything that must be trusted –access control, authorization and authentication procedures, cryptography,firewalls, virus protection, data backup, and even human administration — in order for the right level of security to work.
Are 802.11b and 802.11g Compatible?
802.11b and 802.11g are both popular standards for Wi-Fi home networking. Can 802.11b and 802.11g gear be mixed on a wireless network, or are they incompatible. 802.11b and 802.11g are compatible if 802.11g is running in mixed-mode (both b and g protocols are active but performance is limited due to 802.11b’s Mbps limit).
What Is Wireless Spread Spectrum Communication?
A set of techniques that have been used in radio communications for decades, spread spectrum is also employed in modern Wi-Fi networking to enhance reliability, increase bandwidth and/or improve security of wireless computer connections.
What is Wi-Fi Bridging Mode?
In Wi-Fi networking, bridging mode allows two or more wireless access points (APs) to communicate
with each for the purpose of joining multiple LANs. A computer’s wireless adapter translates data into a radio signal and transmits it using an antenna.
What is the Routing Engine Architecture?
The Routing Engine handles all the routing protocol processes as well as processes controlling interfaces, router components, system management, and user access. These processes run on top of
a kernel that interacts with the Packet Forwarding Engine.
What is netstat?
You can examine your current routing tables by running the command netstat, as follows: %%%%
What Are the Limitations of WiFi Ad-Hoc Mode Networking?
WiFi ad-hoc mode networking allows devices to connect wirelessly without the need for a central
access point or router. However, ad-hoc WiFi also suffers from some key limitations as described
Are Wireless Networks a Health Hazard?
Prolonged exposure to wireless network devices cause memory loss or other brain damage.
What is ifconfig?
It is always best to start investigating routing problems by making sure that your interfaces are set
up correctly. By running ifconfig, you can see your current interface setup: # ifconfig -a lo0:
flags=849<UP,LOOPBACK,RUNNING,MULTICAST> mtu 8232 inet 127.0.0.1 netmask ff000000 le0:
flags=863<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST> mtu 1500 inet 22.214.171.124
netmask ffffff00 broadcast 126.96.36.199 ether 8:0:20:10:78:d When an interface is brought up, it
automatically creates a route. This route will be to the local network for multipoint interfaces (ether,
FDDI, TR, etc), or to a host for point-to-point interfaces (PPP). If your main interface (le0 in the
above example) is not UP and RUNNING, clearly no routing will be occurring through it. If the
interface is UP, you will also want to examine the inet and netmask entries of your main interface,
and make sure they are set correctly. If the inet is set wrong, check your
/etc/hostname.interfacename file (ie, hostname.le0) and your /etc/hosts file. If the netmask is set
wrong, check your /etc/netmasks file
What is Routing?
The ROUTING TABLE is a table maintained in the kernel that determines how packets are routed to
other systems. A number of programs may add or delete routes from the routing tables, including
route, ifconfig, in.routed and in.rdisc. The routing table consists of three types of routes: HOST
ROUTES are checked first and define a route to just one host. NETWORK ROUTES are checked second
and define a route to all the hosts on one network. DEFAULT ROUTES are used as a catch-all, when
no host or network routes are found to a destination. They usually send to a more knowledgeable
routing machine, which has a better chance of being able to find a host or network route to the
What Is Wibree?
Wibree is not much related to Wi-Fi the name notwithstanding; instead, Wibree is a short-range
wireless technology more comparable to Bluetooth.
Can Wi-Fi Be Turned Off for Computers and Routers?
To save power and somewhat improve your network?s security, you should consider turning off the
Wi-Fi radios on both the router and all computers when not using wireless connections.
Do Wireless Routers Support Hybrid Networks?
Many (but not all) wireless routers support hybrid local area networks containing a mix of wired
Ethernet and WiFi clients.
What is Default gateway?
Gateway simply refers to the two interfaces of the routers that are used to connect two different
networks.In a router you can’t have same network ip for two interfaces it will lead to network
conflict. Here when we connect two different network using a router,the first interface of the router
acts as a gateway for the first network,and the second interface acts as a gateway for the second
In computer networking, a gateway is a node (a router) on a TCP/IP network that serves as an
access point to another network. A default gateway is the node on the computer network that the
network software uses when an IP address does not match any other routes in the routing table.
In home computing configurations, an ISP often provides a physical device which both connects local hardware to the Internet and serves as a gateway. Such devices include DSL modems and cable
In organizational systems a gateway is a node that routes the traffic from a workstation to another
network segment. The default gateway commonly connects the internal networks and the outside
network (Internet). In such a situation, the gateway node could also act as a proxy server and a
firewall. The gateway is also associated with both a router, which uses headers and forwarding tables
to determine where packets are sent, and a switch, which provides the actual path for the packet in
and out of the gateway.
In other words, a default gateway provides an entry point and an exit point in a network.