Technology

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…

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…

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 …

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…