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9. Discuss the significance of DNS.   The DNS translates Internet domain and host names to IP addresses. DNS automatically converts the names we type in our Web browser address bar to the IP addresses of Web servers hosting those sites.   DNS implements a distributed database to store this name and address information for all public hosts on the Internet. DNS assumes IP addresses do not change (are statically assigned rather than dynamically assigned).   The DNS database resides on a hierarchy of special database servers. When clients like Web browsers issue requests involving Internet host names, a piece of software called the DNS resolver (usually built into the network operating system) first contacts a DNS server to determine the server's IP address. If the DNS server does not contain the needed mapping, it will in turn forward the request to a different DNS server at the next higher level in the hierarchy. After potentially several forwarding and delegation messages …

10. Explain about voice over IP.   VoIP stands for Voice over Internet Protocol.  VoIP is a technology that allows telephone calls to be made over computer networks like the Internet. VoIP converts analog voice signals into digital data packets and supports real-time, two-way transmission of conversations using Internet Protocol (IP). VoIP calls can be made on the Internet using a VoIP service provider and standard computer audio systems. Alternatively, some service providers support VoIP through ordinary telephones that use special adapters to connect to a home computer network. Many VoIP implementations are based on the H.323 technology standard.     VoIP offers a substantial cost savings over traditional long distance telephone calls. The main disadvantage of VoIP is a greater potential for dropped calls and degraded voice quality when the underlying network links are under heavy load. SAP Client Copy – Local, Remote & Import / export What is…

Explain about OSI reference model.   11. Explain about OSI reference model.  Also describe other network models. SAP Architecture The OSI, or Open System Interconnection, model defines a networking framework to implement protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy. The OSI model takes the task of internetworking and divides that up into what is referred to as a vertical stack that consists of the following layers: What is SAP R3 Architecture ? Physical (Layer 1) This layer conveys the bit stream - electrical impulse, light or radio signal -- through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with ph…

Discuss the features of cellular telephone.   Accessories — Manufacturers offer a number of accessories that can make phones even more convenient to use, such as hands-free options (headsets, ear buds, bluetooth hands free devices), extra batteries, and portable charging adapters.     SAP Client Copy – Local, Remote & Import / export What is SAP Landscape? Battery Type — NiMH (nickel-metal hydride) and Li-ion (lithium ion) are the two primary types of mobile phone batteries. Li-ion is longer-lasting and lighter, but more expensive. Phones use more battery life during calls than when they are turned on but not in use.   Bluetooth — This wireless communications technology links compatible mobile phones, personal computers, PDAs, hands free devices, and other devices across short ranges. To ensure compatability with current devices, look for bluetooth version 2.0.   Caller ID — A feature that displays the name and/or number of the calling party on the p…

5. What is meant by frame relay?   Frame relay is a data link network protocol designed to transfer data on Wide Area Networks (WANs). Frame relay works over fiber optic or ISDN lines. The protocol offers low latency and to reduce overhead, does perform any error correction, which is instead handled by other components of the network. Frame relay has traditionally provided a cost-effective way for telecommunications companies to transmit data over long distances. Frame relay has decreased in popularity as companies are gradually migrating their deployments to Internet Protocol (IP) based solutions.   SAP Client Copy – Local, Remote & Import / export 6. Discuss about multicast routing. What is SAP Landscape? What is SAP R3 Architecture ? SAP Architecture SAP System Administration Transactions – 1

7. Explain about congestion control.   Congestion is an important issue that can arise in packet switched network. Congestion is a situation in Communication Networks in which too many packets are present in a part of the subnet, performance degrades. Congestion in a network may occur when the load on the network (i.e. the number of packets sent to the network) is greater than the capacity of the network (i.e. the number of packets a network can handle.)     SAP Client Copy – Local, Remote & Import / export SAP System Administration Transactions – 1 In other words when too much traffic is offered, congestion sets in and performance degrades sharply.   What is SAP Landscape? What is SAP R3 Architecture ? SAP Architecture

8. Discuss about Application layer security.   Application Layer Security :   Application layer security refers to methods of protecting Web applications at the application layer (layer 7 of the seven-layer OSI model) from malicious attacks that may expose private information. Security is applied to the application layer specifically to protect against unauthorized access and attacks. SAP System Administration Transactions – 1   SAP Client Copy – Local, Remote & Import / export Application Security Manager provides proactive application-layer protection by understanding and analyzing a user's interaction with the application firewall. Application Security Manager is automatically configured to allow only authorized application transactions, protecting networks and critical data from application attacks including hacking, cross-site scripting, and parameter tampering. Capabilities such as packet inspection and behavior analysis protect against mal…

Explain about TDM.     Time Division Multiplexing processes information of different transmitters successively in defined time segments for transmission over one channel. Time Division Multiplexing is differentiated in synchronous and asynchronous multiplexing.   Asynchronous Time Division Multiplexing   Single data streams are classified in variable time segments and subsequently transmitted using the asynchronous time division multiplexing procedure. Thereby transmission occurs in no definite order. Each time segment receives a channel information number to separate them again in the demultiplexer procedure.   Synchronous Time Division Multiplexing   Using the synchronous method, single data streams are classified in defined time segments for subsequent transmission in predetermined order.     Using this TDM procedure for example 8 x Gigabit Ethernet applications can be multiplexed to one 10 Gigabit signal. In the following this independent 10 Gigabi…

Explain about TDM.     Time Division Multiplexing processes information of different transmitters successively in defined time segments for transmission over one channel. Time Division Multiplexing is differentiated in synchronous and asynchronous multiplexing.     Asynchronous Time Division Multiplexing   Single data streams are classified in variable time segments and subsequently transmitted using the asynchronous time division multiplexing procedure. Thereby transmission occurs in no definite order. Each time segment receives a channel information number to separate them again in the demultiplexer procedure.   Synchronous Time Division Multiplexing   Using the synchronous method, single data streams are classified in defined time segments for subsequent transmission in predetermined order.     Using this TDM procedure for example 8 x Gigabit Ethernet applications can be multiplexed to one 10 Gigabit signal. In the following this independent 10 Gigabit s…

Discuss about SONET   Synchronous optical networking (SONET) is a standardized digital communication protocol that is used to transmit a large volume of data over relatively long distances using a fiber optic medium. With SONET, multiple digital data streams are transferred at the same time over optical fiber using LEDs and laser beams.   SONET is a product of the American National Standards Institute (ANSI).   SONET is not that different from other technologies, but hardware was manufactured to provide better configuration and reliable services to its users. SONET may use a re-generator for long haul distances. This device boosts signals that have already traveled for a long distance. Signals are transmitted into electrical signals and then re-generated into high-power signals. Add drop multiplexers (ADMs) are also common parts of SONET. ADMs are designed to fully support the network architecture of SONET. SONET supports multiple data streams at the same time. It was de…

Describe the importance of the physical layer.   The physical layer, the lowest layer of the OSI model, is concerned with the transmission and reception of the unstructured raw bit stream over a physical medium. It describes the electrical / optical, mechanical, and functional interfaces to the physical medium, and carries the signals for all of the higher layers. It provides:   Data encoding: modifies the simple digital signal pattern (1s and 0s) used by the PC to better accommodate the characteristics of the physical medium, and to aid in bit and frame synchronization. It determines:   What signal state represents a binary 1   How the receiving station knows when a "bit-time" starts How the receiving station delimits a frame Physical medium attachment, accommodating various possibilities in the medium.   Transmission technique: determines whether the encoded bits will be transmitted by baseband (digital) or broadband (analog) signaling.     Physical medium…

Discuss about SONET   Synchronous optical networking (SONET) is a standardized digital communication protocol that is used to transmit a large volume of data over relatively long distances using a fiber optic medium. With SONET, multiple digital data streams are transferred at the same time over optical fiber using LEDs and laser beams. SONET is a product of the American National Standards Institute (ANSI).   SONET is not that different from other technologies, but hardware was manufactured to provide better configuration and reliable services to its users. SONET may use a re-generator for long haul distances. This device boosts signals that have already traveled for a long distance. Signals are transmitted into electrical signals and then re-generated into high-power signals. Add drop multiplexers (ADMs) are also common parts of SONET. ADMs are designed to fully support the network architecture of SONET. SONET supports multiple data streams at the same time. It…