1. What is OSI model and how is it important in networking?

The OSI model is the one which divides the network communication as consisting of 7 different layers. These include all the layers between the lower-most physical layer and the higher level Application layer ( Datalink, Network, Transport, Session and presentation layers). What it does by categorizing so is to just distinguish the various functionalities that the protocols may offer over a network transmission. Some of the soecific protocols just try to concentrate the details till the layer necessary, thereby making it simpler for the co-existence of different protocols and different standards.


2. What are the layers that are present in the DOD and the TCP/IP models?

The TCP/IP networking model consists of the Application, transport, network, datalink and physical layers. The DOD model has the application, host-to-host, internet, network access layers – 4 in total.


3. What is the type of cable used for connecting similar devices?

The similar devices are usually connected using the cross wired cables. This  reduces the noise and enable smooth communication. 1,2 pins of the cross wire and meant for sending and 3,6 points are for reception of data.


4. What are the advantages of twister pair cables?

The twisted pair has two independent wires insulated with plastic coating and interwoven with each other. This type of insulation prevents cross talk and avoids the undesirable induction effects from magnetic fields which may generate losses and corruptions. These can be used to carry signal over reasonable distances.


5. Briefly describe the RIP.

The Routing Information Protocol is one that is used to give the routing information along with the data that is being sent. This has become obsolete with emergence of large networks and the internet. However, in the local internal networks with fixed number of hop spots, the RIP can serve as an efficient way to transfer data from one point to another. The router need not do much of work in identifying the shortest route etc.


6. How does ARP differ from RARP?

The ARP (Address Resolution Protocol) is meant for the identification of a remote system’s physical address, when the host knows only its network address. The Reverse ARP (RARP) is used when the host wants to know its own network address when all it has is the physical address of itself.


7. What is the difference between the TCP and UDP protocols? When are they used?

The TCP is a connection oriented protocol while the UDP is not. This means that the TCP based communication is more reliable than the UDP. The sequence of acknowledgements that are associated with TCP makes it more effective for transmission of control information and other important commands. The UDP on the other hand makes it possible to have a quick transmission of data across the various systems in the network. This is used when a few packet losses are not a matter of concern (like in Live video streaming).


8. How is bit rate different from baud rate of a network?

The bit rate represents the number of bits that are transferred in one second. But the baud rate refers to the number of signals at the hardware level that are transmitted in one second. The baud rate is thus obtained by dividing the bit rate by the N (number of signal units per bit).


9. What is Remote Procedure Call (RPC)?

RPC refers to the mechanism of invoking a function that is implemented in a remote system through the network. The RPCs can be performed using many different protocols and standards. The usual standards are based on the XML based data that is being transferred across the TCP protocol from one system to another.


10. What is a subnet? What is a subnet mask?

The subnet refers to the dividing of a network based on the network addresses that are assigned. This way the security of the networks are established according to the different sub-networks and the huge network can be made easily manageable based on the divisions. The subnet mask refers to the number which identifies the significant values in the address of the systems. For example a mask of establishes the fact that the sub-network is having only 255 systems that are distinguished by the last part of the IPV4 address.


11. What is a FTP?

The File Transfer Protocol is one that is designed to enable quick transfer of files from one system to another. The file servers that are deployed have the ports listening for incoming FTP requests. The requests for specific files from clients are then responded with the link to the file that they request.


12. What are transaction server?

Transaction server refers to the server with a database engine to which the other systems send remote procedure calls. These calls in turn will be signalling a batch execution of the SQL statement from the database. The SQL queries succeed or fail as a batch. The entire message transfer between the transaction server and a client is in the single request/reply model.


13. What is horizontal and vertical scaling?

The horizontal scaling refers to the expansion of the client or workstation base in a server/client based network. This may indicate increase in number of clients or increase of client dependency on the server – meaning a additional load on the servers.  The vertical scaling on the other hand refers to server expansion in number or performance power.


14. What are sockets and ports? How many ports are available on a normal system?

Sockets represent the end points of communication. Assuming a channel of communication established between two systems, the endpoint in which each system received or sends data is referred to as sockets. Ports refer to the outlets through which the system can be connected with others. The number of ports in a normal operating system is 65536. The first 1024 ports are allocated for general usage and system functionalities.


15. What is two-tier architecture?

A 2-tier architecture refers to the server-client model of networking. Here the applications are entirely residing on the server side with minimal operations on the client side. Most of the time it is just the user interface that lies in the client side and all the computations are carried out in the server side of the application. Database server and print server are typical examples of such an architecture.


16. What is a general middleware?

The general middleware is one that is lying below the UI application and this consists of all the communicative procedures like RPCs, authentication procedures, network/OS extensions with queuing services etc. This is a platform below which a complex storage mechanism or any complex logic is implemented and over which the development of different access mechanisms takes place.


17. What is meant by beaconing?

This is the mechanism of auto-repair in the networks like the ring and FDDI. The network hotspots can detect any misled transmission or malfunctions in the network. This can again be used within the network to make it repair the condition by itself.


18. What is the difference between NETBIOS and NETBEUI?

The NETBIOS is the abstracting layer of software there hides the hardware specifics of the network from the applications. The NETBEUI refers to the user interface (NETBIOS extended User Interface) that gives access to the NETBIOS functions like sending and receiving messages through the network interface.


19. What is the difference between the hub and switch?

The hub is just a junction where the systems are integrated but there is no logically divided network. Any packet received through a hub is sent across to all the other members connected to the hub (which is then resolved using Collision detection mechanisms). It can have a max speed of 10mbps. The switch creates a logically divided network with all the systems having a logical network address for each system and the max speed achievable is 100mpbs.


20. What is network cluster?

The cluster is the network logic that combines the resources and processing powers of many systems and identifies it as a single entity. Distributed systems and Network of Workstations come under such kind. The cluster usually has a merged network identity within which there can be individually separate systems with their own identity.


21. What is attenuation? How is it overcome?

The attenuation refers to the degradation of signal strength when it is transmitted for a long distance over cables. This is overcome be placing repeaters at specific distances.


22. What are the different types of transparencies that NOW middleware provides you?

The different types of transparencies include namespace, failure, administration, distributed time, location , logon, access transparencies.


23. What is DHCP?

The DHCP stands for Dynamic Host Configuration Protocol which is responsible for identifying the unused network addresses from the particular hotspot and assigning it to the specific system. This applies to the IP networks of computers where many intermediate routers.


24. What is an Object server?

With an object server, the Client/Server application is written as a set of communicating objects. Client object communicate with server objects using an Object Request Broker (ORB). The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together.


25. What is a Transaction server? 

With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request/reply message. The SQL statements either all succeed or fail as a unit.


26. 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.


27. What are the most typical functional units of the Client/Server applications? 

User interface

Business Logic and 

Shared data.


28. What are all the Extended services provided by the OS?

Ubiquitous communications 

Network OS extension

Binary large objects (BLOBs)

Global directories and Network yellow pages

Authentication and Authorization services

System management

Network time

Database and transaction services

Internet services

Object- oriented services


29. 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.


30. What is meant by Transparency? 

Transparency really means hiding the network and its servers from the users and even the application programmers.


31. What are TP-Lite and TP-Heavy Monitors? 

TP-Lite is simply the integration of TP Monitor functions in the database engines. TP-Heavy are TP Monitors which supports the Client/Server architecture and allow PC to initiate some very complex multiserver transaction from the desktop.


32. What are the two types of OLTP? 

TP lite, based on stored procedures. TP heavy, based on the TP monitors.


33. What is a Web server? 

This new model of Client/Server consists of thin, protable, "universal" clients that talk to superfat servers. In the simplet form, a web server returns documents when clients ask for them by name. The clients and server communicate using an RPC-like protocol called HTTP.


34. What are Super servers? 

These are fully-loaded machines which includes multiprocessors, high-speed disk arrays for intervive I/O and fault tolerant features.


35. What is a TP Monitor? 

There is no commonly accepted definition for a TP monitor. According to Jeri Edwards' a TP Monitor is "an OS for transaction processing".


36. TP Monitor does mainly two things extremely well. They are Process management and Transaction management.? 

They were originally introduced to run classes of applications that could service hundreds and sometimes thousands of clients. TP Monitors provide an OS - on top of existing OS - that connects in real time these thousands of humans with a pool of shared server processes.


37. What is meant by Asymmetrical protocols?

There is a many-to-one relationship between clients and server. Clients always initiate the dialog by requesting a service. Servers are passively awaiting for requests from clients.


38. What are the types of Transparencies? 

The types of transparencies the NOS middleware is expected to provide are:-

Location transparency

Namespace transparency

Logon transparency

Replication transparency

Local/Remote access transparency

Distributed time transparency

Failure transparency and

Administration transparency.


39. What is the difference between trigger and rule? 

The triggers are called implicitly by database generated events, while stored procedures are called explicitly by client applications.


40. What are called Transactions? 

The grouped SQL statements are called Transactions (or) A transaction is a collection of actions embused with ACID properties.


41. What are the building blocks of Client/Server? 

The client

The server and



42. Explain the building blocks of Client/Server? 

The client side building block runs the client side of the application.

The server side building block runs the server side of the application.


43. What are all the Base services provided by the OS? 

Task preemption

Task priority


Interprocess communications (IPC)

Local/Remote Interprocess communication


Intertask protection


High performance file system

Efficient memory management and

Dynamically linked Run-time extensions.


44. What are the roles of SQL? 

SQL is an interactive query language for ad hoc database queries.

SQL is a database programming language.

SQL is a data definition and data administration language.

SQL is the language of networked database servers

SQL helps protect the data in a multi-user networked environment.

Because of these multifacted roles it plays, physicists might call SQL as "The grand unified theory of database".


45. What are the characteristics of Client/Server? 


Shared resources

Asymmentrical protocols

Transparency of location


Message based exchanges

Encapsulation of services



Client/Server computing is the ultimate "Open platform". It gives the freedom to mix-and-match components of almost any level. Clients and servers are loosely coupled systems that interact through a message-passing mechanism. 


46. What is Structured Query Langauge (SQL)?

SQL is a powerful set-oriented language which was developed by IBM research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible, commands that can be used to manipulate information collected in tables. Through SQL, we can manipulate and control sets of records at a time.


47. What is Remote Procedure Call (RPC)? 

RPC hides the intricacies of the network by using the ordinary procedure call mechanism familiar to every programmer. A client process calls a function on a remote server and suspends itself until it gets back the results. Parameters are passed like in any ordinary procedure. The RPC, like an ordinary procedure, is synchoronous. The process that issues the call waits until it gets the results. 

Under the covers, the RPC run-time software collects values for the parameters, forms a message, and sends it to the remote server. The server receives the request, unpack the parameters, calls the procedures, and sends the reply back to the client. It is a telephone-like metaphor.


48. What are the main components of Transaction-based Systems? 

Resource Manager

Transaction Manager and

Application Program.


49. What are the three types of SQL database server architecture? 

Process-per-client Architecture. (Example: Oracle 6, Informix )

Multithreaded Architecture. (Example: Sybase, SQL server)

Hybrid Architecture


50. What are the Classification of clients? 

Non-GUI clients - Two types are:-

Non-GUI clients that do not need multi-tasking

(Example: Automatic Teller Machines (ATM), Cell phone)

Non-GUI clients that need multi-tasking

(Example: ROBOTs)


GUI clients

OOUI clients


51. What are called Non-GUI clients, GUI Clients and OOUI Clients? 

Non-GUI Client: These are applications, generate server requests with a minimal amount of human interaction.

GUI Clients: These are applicatoins, where occassional requests to the server result from a human interacting with a GUI

(Example: Windows 3.x, NT 3.5)

OOUI clients : These are applications, which are highly-iconic, object-oriented user interface that provides seamless access to information in very visual formats.

(Example: MAC OS, Windows 95, NT 4.0)


52. What is Message Oriented Middleware (MOM)? 

MOM allows general purpose messages to be exchanged in a Client/Server system using message queues. Applications communicate over networks by simply putting messages in the queues and getting messages from queues. It typically provides a very simple high level APIs to its services. 

MOM's messaging and queuing allow clients and servers to communicate across a network without being linked by a private, dedicated, logical connection. The clients and server can run at different times. It is a post-office like metaphor.


53. What is meant by Middleware? 

Middleware is a distributed software needed to support interaction between clients and servers. In short, it is the software that is in the middle of the Client/Server systems and it acts as a bridge between the clients and servers. It starts with the API set on the client side that is used to invoke a service and it covers the transmission of the request over the network and the resulting response. 

It neither includes the software that provides the actual service - that is in the servers domain nor the user interface or the application login - that's in clients domain.


54. 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.


55. 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.


56. What are General Middleware? 

It includes the communication stacks, distributed directories, authentication services, network time, RPC, Queuing services along with the network OS extensions such as the distributed file and print services. 


57. What are Service-specific middleware?

It is needed to accomplish a particular Client/Server type of services which includes:-

Database specific middleware

OLTP specific middleware

Groupware specific middleware

Object specific middleware

Internet specific middleware and

System management specific middleware.


58. 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.


59. 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.


60. What is meant by 3-Tier architecture? 

In 3-tier Client/Server systems, the application logic (or process) lives in the middle tier and it is separated from the data and the user interface. In theory, the 3-tier Client/Server systems are more scalable, robust and flexible. 

Example: TP monitor, Web.


61. 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 procedures.


62. What is Load balancing? 

If the number of incoming clients requests exceeds the number of processes in a server class, the TP Monitor may dynamically start new ones and this is called Load balancing.


63. 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.


64. What is meant by Horizontal scaling and Vertical scaling? 

Horizontal scaling means adding or removing client workstations with only a slight performance impact. Vertical scaling means migrating to a larger and faster server machine or multiservers.


65. 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 other people.


66. What are the two broad classes of middleware? 

General middleware

Service-specific middleware.


67. What are the types of Servers? 

File servers

Database servers Transaction servers Groupware servers Object servers Web servers. 


68. What is a File server? 

File servers are useful for sharing files across a network. With a file server, the client passes requests for file records over nerwork to file server.


69. What are the five major technologies that can be used to create Client/Server applications? 

Database Servers

TP Monitors


Distributed Objects



70. 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.


71. List out the benefits obtained by using the Client/Server oriented TP Monitors? 

Client/Server applications development framework.

Firewalls of protection.

High availability.

Load balancing.

MOM integration.

Scalability of functions.

Reduced system cost.


72. What are the services provided by the Operating System? 

Extended services - These are add-on modular software components that are layered on top of base service.


73. What is ACID property? 

ACID is a term coined by Andrew Reuter in 1983, which stands for Atomicity, Consistence, Isolation and Durability.


74. What are Stored procedures? 

A stored procedure i s named collection of SQL statements and procedural logic that is compiled, verified and stored in a server database. It is typically treated like any other database object. Stored procedures accept input parameters so that a single procedure can be used over the network by multiple clients using different input data. A single remote message triggers the execution of a collection of stored SQL statements. The results is a reduction of network traffic and better performance.


75. What is wide-mouth frog? 

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.


76. 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.


77. What is region? 

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.


78. 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.


79. Difference between the communication and transmission? 

Transmission is a physical movement of information and concern issues like bit polarity, synchronization, clock etc. 

Communication means the meaning full exchange of information between two communication media.


80. 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 offered 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.


81. 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.


82. 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.


83. What does the Mount protocol do ?

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.


84. 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.


85. What is the HELLO protocol used for? 

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.


86. 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 the PAD and the network, called X.29. Together, these three recommendations are often called "triple X".


87. What is attenuation? 

The degeneration of a signal over distance on a network cable is called attenuation. 


88. 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).


89. Name the port used by PING.

Always remember that PING does not use any port. As PING is based upon layer 3 protocol, it never uses any computer port. A simple variation of the question could be: Does PING use UDP? Or Does PING use TCP? Again remember that UDP and TCP are layer 4 protocols and PING has nothing to do with them.


90. 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.


91. 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.


92. 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.


93. What is terminal emulation, in which layer it comes? 

Telnet is also called as terminal emulation. It belongs to application layer.


94. 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.

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. 


95. 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.


96. What is multicast routing? 

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing. 


97. 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.


98. What are the different type of networking / internetworking devices? 


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.


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.


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.


99. 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.


100. 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.


101. 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.


102. Why should you care about the OSI Reference Model? 

It provides a framework for discussing network operations and design. 


103. What is Proxy ARP?

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.


104. 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.


105. 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.


106. What is Mail Gateway? 

It is a system that performs a protocol translation between different electronic mail delivery protocols.


107. What is RIP (Routing Information Protocol)? 

It is a simple protocol used to exchange information between the routers.


108. 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.


109. 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.


110. 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).