All in one q & ans


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All in one q & ans

  1. 1. All in one Q and AnsWhat do you mean by the term ‘routing’? What a router must know to route a packet?‘Routing’ is used to deliver a packet from one device to another device through communicationnetwork. Routing is performed by the router and each router maintains a routing table. A routing tablecontains the information of the best possible paths from source router to the destination router.A router must know the following to route a packet:a. Address of the destinationb. Neighbor routersc. Routes to all remote networksd. The best route to each remote networke. Way to maintain and verify routing informationComment on Static Routing, Default Routing and Dynamic Routing.To route a packet over the communication network, a network administrator has to configure a router.These configurations are of three types:Static Routing: A network administrator manually configures the routes for a router. A static route hashigher priority than a dynamic route.Default Routing: Default routing is used only for the network that has only a single connection torouter. Static routes are also manually configured.Dynamic Routing: Dynamic routing used various routing protocols to route packets. A route isautomatically updated as a topology change occurs. Dynamic routing is easier than static and defaultrouting.How many classes of routing protocols are there. Describe each?There are three classes of routing protocols: Distance vector, Link State and HybridDistance Vector: This routing protocol discover the best path to a remote network by judging distance.This type of protocols counts the hop; hops are the number of the routers from which a packet goes.The vector points to the direction of remote network.
  2. 2. Example: RIP and IGRP.Link State: A router send updates containing the state of their own link to the other routers. This isalso called shortest path first protocol. Three different tables are maintained by the router using thisprotocol. One is routing table, one of directly attached neighbors and one for the topology of entireinternetwork. Link state enables a router to know about internetwork.Example: OSPF.Hybrid: Hybrid protocols contain the features of both Distance vector and link state protocols.Why do Routing Loops occur and how to overcome them?a) Routing loop is common problem of various types of networks. Distance vector routing protocolkeeps track of any change to the internetwork by broadcasting periodic updates. This works okay butif a network outage happens then routing loops occurs in the network. The main reason to occurrouting loops is that each router is not updated at the same time and the fake information of a router’slink broadcasted.Three rules for distance vector routing protocol are developed to overcome routing loops:i. Split Horizon: According to this rule, never broadcast a route out of the interface through which itreceived. It helps to avoid loops between adjacent routers.ii. Route Poisoning: When a network goes down than the router associated to that network initiatesroute poisoning. This shows an unreachable network.iii. Holddown timer: Holddown timer says that if a route advertised as down, do not listen to routingupdates from that route for a specified period of time.Define OSPF and what features are provided by OSPF?OSPF is abbreviated as Open Shortest Path First. OSPF is an open standard and supported by alarge variety of network vendors, including Cisco. OSPF works on the concept of Dijkstra algorithm inwhich a shortest path is maintained and routing table is populated on that path.Some features of OSPF are:i. Minimizes routing update trafficii. Open standard routing protocoliii. Unlimited hop countiv. Routing update traffic is lesser than any other routing protocol.
  3. 3. Define Routing Information Protocol (RIP) and what is the difference between RIPv1 andRIPv2?RIP is a distance vector routing protocol which uses hop count to find the best way to a remotenetwork. RIP sends its complete routing table to neighbor router in every 30 seconds. RIP usesmaximum 15 hop count and is suitable only for small networks.RIPv1 uses classful routing that means all the devices in the network must use the same subnetmask and do not send subnet mask information with routing updates. While RIPv2 uses classlessrouting and subnet mask information is sent with routing update.What is IGRP? Differentiate between IGRP and RIP.IGRP is abbreviated as Interior Gateway Routing Protocol. This is created by Cisco and all therouters must be of Cisco to run this protocol. IGRP is developed to overcome the problem with RIP.RIP can be used only for small network because it uses maximum 15 hop-counts while IGRP can beused for bigger networks because it uses 255 hop-counts.i. IGRP uses autonomous system number and supplies this number to all routers while in RIP there isno autonomous number.ii. IGRP updates its Routing table every 90 seconds and RIP updates its routing table in every 30seconds.iii. IGRP has administrative distance of 100 while RIP has 120.iv. IGRP uses maximum 255 hop-counts while RIP uses 15 maximum hop-counts.What is EIGRP and what conditions are needed to neighbourship establishment in context toEIGRP?EIGRP is abbreviated as Enhanced Interior Gateway Routing Protocol. EIGRP is a proprietary Ciscoprotocol that runs only on Cisco routers. EIGRP is a popular routing protocol now days. EIGRP is aclassless, enhanced distance routing protocol.Before EIGRP routers wants to exchange routes, they have to establish a neighborhood relationship.To establish this neighbourship three conditions must meet:i. Autonomous System Numbers must matchii. Hello packet must receivediii. Metrics value must identical
  4. 4. OSPF is supposed to be design in a hierarchical fashion; what are the reasons for creatingOSPF in a hierarchical fashion?OSPF (Open Shortest Path First) is supposed to be design in hierarchical fashion so that a largeinternetwork could be break into smaller network. These smaller networks are called areas.Following are some reasons for creating OSPF in hierarchical design:i. To reduce the routing overheadii. To break a bigger internetwork into smaller internetworks caller areasiii. To accelerate convergenceWhat do you mean by ‘Switching’? What are the services provided by Switching?Generally switching refers to the layer 2 switching. Switching is a process which uses the hardwareaddress or MAC address of a device to switch a packet from one device to another.Services provided by switching are:i. Switches use Application-Specific Integrated Circuits (ASICs) to make and maintain their filter table.ii. Time required to transfer a packet is low i.e. low latencyiii. Cost is lowWhat is Spanning Tree Protocol (STP) and define some STP terms?The main function of STP is to prevent the network loops occurring in switching network. STPmonitors the network to find all links and shut down the redundant links. For this STP uses Spanningtree algorithm.Some STP terms are:Root Bridge: To select a root bridge an election is done by all switches in a switching network. All thedecisions like- which port is to be blocked and which port is forwarding are made from the viewpointof Root Bridge.BPDU: BPDUs (Bridge Protocol Data Unit) are sending from one switch to another to elect a rootbridge.Bridge ID: Bridge ID is an identifier of a Switch.Three switch functions are address learning, forward/filter decision, loop avoidance. Definethese functions.
  5. 5. Address Learning: In Layer 2 switching, each interface of a switch learns the source hardwareaddress (MAC address) and save this into its MAC database table. This table is also known asforward filter table.Forward/filter decisions: Forward/filter decision is taken by the switch to forward a frame to a specificdestination port. The frame which comes on an interface, switch sees its MAC address table andforward this frame to a specific destination port.Loop Avoidance: Network loops can arise if multiple connections are formed between switches forredundancy purposes. TO prevent network loops STP (Spanning Tree Protocol) is used andredundancy is also maintained.How STP works and what is the purpose for STP?Firstly STP elects a Root Bridge and forward to all ports and this root bridge acts as a point ofreference for all other devices in STP domain. When all switches agreed on root bridge, every switchmust find its one and only allotted root port. Each and every link between switches must have oneand only one designated port in such a way that it must provide the highest bandwidth to link.The main purpose for STP is to prevent the network loops.Define Spanning-Tree port states.The port of switches running STP can has five different port state:- Blocking: A blocking port only listens to BPDUs while cannot forward frames.- Listening: Listening port only listen to BPDUs and preparing to forward frames.- Learning: The switch listen to BPDUs and learns all the paths in the LAN network.- Forwarding: In this port state, switch port can forward and receive the frames.- Disabled: In disabled state a switch port is administratively down and that port do not participateframe forwarding.What are Manageable and unmanageable switches? What is the advantage of manageableover unmanageable?Manageable Switch: Managed switches allows the layer 3 functionality and can be used as a router. Ithas own IP address and can be easily configured. It also has ability to traffic control, port blockingand VLANs configuration.Unmanageable Switch: Unmanageable switches are layer 2 switches and learn only hardwareaddress (MAC address). It learns the MAC address of all the connected devices and when a framecame from some source it broadcast it to all ports and throws frame to destination (by using its MAC
  6. 6. table).Advantages of manageable over unmanageable are:i. IP address can be assigned to manageable switch and can it can be access through ‘telnet’command.ii. More secure than unmanageable because any port can be block at any time.iii. Managed switch has router like capabilities.iv. Managed switch can manage the bandwidth of link.If your routing table has a static, a RIP, and an IGRP route to the same network, by defaultwhich route will be used to route packets?Administrative distance rates the trustworthiness of the any routing protocol. AD value is an integerfrom 0 to 255 and trustworthiness increases with the increasing order of the AD value.Static route will be used to route packets. Static routes have an administrative distance of 1 bydefault. IGRP has an administrative distance of 100, and RIP has an administrative distance of 120,by default.If a switch receives a frame and the source MAC address is not in the MAC address table butthe destination address is, what will switch do with the frame?Since the source MAC address is not in the MAC address table, firstly the switch will add the sourceMAC address and the port it is connected to into its MAC address table and then forward the frame tothe outgoing port and frame reached to the right destination address.If you want to improve switched network performance by increasing the bandwidth availableto hosts and limit the size of broadcast domains. Which of the following options will achievethis goal—(i) Bridges, (ii) Switches or (iii) Switches configured with VLANs?Switches configured with VLANs will improves the network performance. By creating andimplementing VLANs in our switched network, we can break up broadcast domain and limit the sizeof broadcast domain. VLANs greatly enhance network security which also improves the switchednetwork performance.If two connected routers are configured with RIP routing. What will be the result when a routerreceives a routing update that contains a higher-cost path to network already in its routingtable?
  7. 7. When a routing update is received by a router, the router first checks the administrative distance (AD)value and always choose the route with the lowest administrative distance value. However, if tworoutes are received and they both have same administrative distance value, then the router willchoose the one route with the lowest metrics, or in RIP’s case, hop count.RIP allows a maximum hop-count of 15, so anything that requires 16 hops is consider asunreachable. Hence if a router receives a routing update that contains a higher-cost path but havelower hops than the packet will be transferred through that path.What is Ethernet technology?Ethernet technology is a high speed broadcast bus technology. In this type, all the station shares asingle ether channel and receives every single transmitted signal.Explain token ring technology.In this technology, all the devices are arranged in a circle. A token moves around the circular network.A device waits for the token before it sends its frame. Once it receives token, it initiates transmissionof its frame.What is Application layer?The application layer is located at the top of the TCP/IP protocol layers. This one contains thenetwork applications which make it possible to communicate using the lower layers. The software inthis layer therefore communicates using one of the two protocols of the layer below (the transportlayer), i.e. TCP or UDP. In computer networking, an application layer firewall is a firewall operating atthe application layer of a protocol stack.[1] Generally it is a host using various forms of proxy serversto proxy traffic instead of routing it. As it works on the application layer, it may inspect the contents ofthe traffic, blocking what the firewall administrator views as inappropriate content, such as certainwebsites, viruses, and attempts to exploit known logical flaws in client software, and so forth. Anapplication layer firewall does not route traffic on the network layer. All traffic stops at the firewallwhich may initiate its own connections if the traffic satisfies the rules.What is CSMA and CD concept?In CSDA (carrier sense multiple access), presence of any digital signal in a network is checked beforetransmission. Data transmission occurs only when no signal is sensed.CD, Collision detection is responsible for monitoring carrier in order to avoid signal jamWhat is NetBIOS protocol?
  8. 8. NetBIOS (Network Basic Input/Output System) Protocol allows applications on separate computers tocommunicate over a LAN. It runs over TCP/IP giving each computer in the network a NetBIOS nameand IP address. E.g. It can be used for computers running Windows 2000 (or before) to join acomputer network running Windows 2000 (or later).What is IGMP protocol?Internet Group Management Protocol, allows internet hosts to multicast. i.e. to send messages to agroup of computers. There may be a group of internet hosts interested to multicast. IGMP allowsrouter to determine which host groups have members on a given network segment. It helps toestablish group memberships. It is commonly used for streamlining videos and gaming. The protocolcan be implemented both as a host side and router side. The host side is responsible to notify itsmembership in a group. The notification is made to a local router. This local router (router side) in turnsends out queries.Define DNSThe DNS translates Internet domain and host names to IP addresses. DNS automatically convertsthe names we type in our Web browser address bar to the IP addresses of Web servers hostingthose sites. DNS implements a distributed database to store this name and address information for allpublic hosts on the Internet.What is TCP / IP protocol?Transmission Control Protocol / Internet Protocol: - It is a family of protocols used for communicationand connection between hosts on the internet. It is the most widely used standard for transmittingdata over the internet. The four layers in the protocol are (from bottom to top):- Physical layer, Datalink layer, Network layer, transport layer and application layer, also called as the OSI model. InTCP/IP , IP is responsible for forwarding packets while TCP ensures the correct delivery of data fromclient to server. TCP detects loss of data as wellDefine SMTP.SMTP - Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages betweenservers.What Is a MAC Address?MAC (Media Access Control) addresses are globally unique addressed that are written into hardwareat the time of manufacture. The MAC address is a unique value associated with a network adapter.
  9. 9. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identifyan adapter on a LAN. MAC addresses are 12-digit hexadecimal numbers (48 bits in length).What is HTTP (Hypertext Transfer Protocol)?HTTP or Hyper Text Transfer Protocol is provides a set of rules to transfer files, videos, images overthe world wide web. When the web browser is opened, a HTTP request call is made. A web servercontains a HTTP daemon. This daemon is used to wait for HTTP requests and handle them whenthey arrive. The web browser from where HTTP requests are made is called as a client. Theserequests are sent to the server. It uses a reserved port no 80.What is NNTP (Network News Transfer Protocol)?NNTP or Network News Transfer Protocol is used to manage the notes posted on Unset newsgroup(a collection of posted notes on a subject posted by different users). NNTP servers are responsiblefor managing Usenet newsgroup collected globally. A NTTP client is a part of the web browser alsocalled as a news reader. It uses a reserver port no 119What is POP3 (Post Office Protocol 3)?POP3 or Post Office Box 3 is used fro receiving emails. It is a client server protocol which holds theemail. Once the email is downloaded from the server, POP3 deletes it from the server. Ordinalnumbers are used to identify specific messages.MAC vs. IP AddressingWhereas MAC addressing works at the data link layer, IP addressing functions at the network layer(layer 3). Its a slight oversimplification, but one can think of IP addressing as supporting the softwareimplementation and MAC addresses as supporting the hardware implementation of the networkstack. The MAC address generally remains fixed and follows the network device, but the IP addresschanges as the network device moves from one network to another.Define Spanning-Tree Protocol (STP)Spanning-Tree Protocol (STP) as defined in the IEEE 802.1D is a link management protocol thatprovides path redundancy while preventing undesirable loops in the network. For an Ethernet networkto function properly, only one active path can exist between two stations. Loops occur in networks fora variety of reasons. The most common reason you find loops in networks is the result of a deliberateattempt to provide redundancy - in case one link or switch fails, another link or switch can take over
  10. 10. What is SNMP (Simple Network Management Protocol)?SNMP or Simple Network Management Protocol is typically used for managing the network.Managing the network includes managing the nodes present in the network. These nodes may beserver, routers, bridges and hubs. SNMP agents are used to achieve this. Managing the network isessential because it helps to monitor network performance, detect network faults or failures, auditnetwork usage etc. the SNMP messages like TRAP, GET or SET may be invoked by networkelements or network management system.What is VPN?A VPN is a service that offers secure, reliable connectivity over a shared public network infrastructuresuch as the Internet. VPNs maintain the same security and management policies as a privatenetwork. They are the most cost effective method of establishing a virtual point-to-point connectionbetween remote users and an enterprise customers network.How would you define IP address?IP address or Internet Protocol address is the address of a device attached to an IP network (TCP/IPnetwork). It is a must for every client, server and network device to have a unique IP address for eachnetwork connection (network interface). Every IP packet contains a source IP address and adestination IP address. As a device moves from one network to another, its IP address changes.Computers using the TCP/IP for communication are uniquely identified by a 32 bit address called asan IP address. The routers use the IP address information to forward the packet to the destinationcomputer.IP addresses are categorized as:Private address: these IP addresses are used exclusively within a private network and not for publicto see.Public Address: these are registered IP addresses used for public.Each IP address has a network address and a host address. IP addresses are expressed in four setsof three numbers, separated with dots. Each set is called as an octet because when converted tobinary; it denotes eight binary.What is Routing table?A routing table stores the routes of the various nodes in a network. Nodes can be any electronicdevice connected to the network. The table is usually stored in a router or the network computer as adatabase or file. This information helps to fond the best possible path. The routing table has at least 3fields: the destination network id, cost of the path, next hop or address to send the packet.
  11. 11. Difference between Static and Dynamic IP.Static IP is also called as permanent address assigned to each device in a network, whereasDynamic IP, a temporary address assigned to the device via DHCP software. IP address assigned toyour service by your cable or DSL Internet provider is typically dynamic IP. In routers and operatingsystems, the default configuration for clients is dynamic IPWhat is Routing Protocols?Routing protocols are used to assist in achieving the basic purpose of routing. They specify therouters the method to communicate with each other. They help the routers select the best possiblepath between nodes. There are different types of protocols such as link-state routing protocols, pathvector protocols and distance vector routing protocols. These protocols prevent routing loops to formor break if formed already. They help to decide preferred routes from a sequence of hop costs.What is Distance Vector Routing Protocols?The main goal of Distance Vector Routing Protocols Is to find out the best path for he data packet toreach the destination. Distance here could be the hops. The three different types of Distance Vectorrouting protocols include:- Routing Information Protocol (RIP v1 and v2) and Interior Gateway RoutingProtocol. The protocol is easy to manage however not well scalable.The Distance Vector protocol initially prepares a Routing table which is shared with other routers.This routing table is shared between routers present in the same network. A new routing table isprepared when some new information is received from some other router. Now, the bad routing pathsare removed keeping only the smallest hop paths. This new table is then communicated to otherrouters.What is the difference between public and private IP?A public IP address allows equipment accessible to everyone on the internet. A private IP address isfor private use within the network and allows many more PCs to be connected. If you are using aprivate IP and wants VOIP, you need to change to a public IP address.Explain Transmission Control Protocol, TCP.TCP ensures reliable and end to end delivery of segments of information. Segments areacknowledged to the source when received by the destination. Data is broken up into segments andsequenced properly before transmission. This arrangement of segments allows destination to tracelost data in transmission.
  12. 12. What is TCP protocol?Transmission control Protocol is used to establish communication between nodes or networks andexchange data packets. It guarantees delivery of data packets in the order they were sent. Hence it ismost commonly used in all applications that require guaranteed delivery of data. It can handle bothtimeouts (if packets were delayed) and retransmission (if packets were lost). The stream of data istransmitted in segments. The segment header is 32 bit. it is a connectionless communication protocolat the third level (network) of the OSI modelTCP vs. UDP.TCP guarantees the delivery of data. UDP on the other hand, does not guarantee delivery of data.TCP delivers messages in the order they were sent. UDP has no ordering mechanisms. In TCP datais sent as a stream while UDP sends data as individual packets. UDP is faster than TCP. TCP is aconnection oriented protocol while UDP is connectionless.What is Network Address Translation?Network Address Translation acts as an agent between the Internet and a local network. It is adynamic method which is used to minimize Internet connectivity needs. Network address translationdescribes the rewriting of the Internet Protocol (IP) addresses of data packets so that multipletransmissions require only one IP addressDefine IP multicast.IP multicast technology reduces traffic by sending stream of information to many recipients at one go.Video conferencing, stock quotas are the examples based on IP multicast.Explain User Datagram Protocol, UDP.The UDP is a connectionless, unreliable service. UDP messages can be lost and duplicatedWhat is UDP protocol?User Data Protocol is a communication protocol. It is normally used as an alternative for TCP/IP.However there are a number of differences between them. UDP does not divide data into packets.Also, UDP does not send data packets in sequence. Hence, the application program must ensure thesequencing. UDP uses port numbers to distinguish user requests. It also has a checksum capabilityto verify the data
  13. 13. TCP vs. UDP.TCP guarantees the delivery of data. UDP on the other hand, does not guarantee delivery of data.TCP delivers messages in the order they were sent. UDP has no ordering mechanisms. In TCP datais sent as a stream while UDP sends data as individual packets. UDP is faster than TCP. TCP is aconnection oriented protocol while UDP is connectionless.What is TCP windowing concept?TCP windowing concept is primarily used to avoid congestion in the traffic. It controls the amount ofunacknowledged data a sender can send before it gets an acknowledgement back from the receiverthat it has received it.What is Trusted and Untrusted Networks?Trusted networks: Such Networks allow data to be transferred transparently. The machines using atrusted network are usually administered by an Administrator to ensure that private and secured datais not leaked. Access to this network is limited. Computers using trusted networks are more securedand confidential because of strong firewalls.Untrusted networks: Such networks are usually administered by the owners. They can allowimproper access to sensitive or personal data. These machines are usually separate. Such machinescould me more prone to attacks.What are the different types of VPN? • Remote Access VPN:- Also called as Virtual Private dial-up network (VPDN) is mainly used in scenarios where remote access to a network becomes essential. Remote access VPN allows data to be accessed between a company’s private network and remote users through a third party service provider; Enterprise service provider. E.g Sales team is usually present over the globe. Using Remote access VPN, the sales updates can be made. • Site to Site VPN – Intranet based: This type of VPN can be used when multiple Remote locations are present and can be made to join to a single network. Machines present on these remote locations work as if they are working on a single network. • Site to Site VPN – Extranet based: This type of VPN can be used when several different companies need to work in a shared environment. E.g. Distributors and service companies. This network is more manageable and reliableWhat are the different authentication methods used in VPNs?The authentication method uses an authentication protocol. The methods are:
  14. 14. • EAP authentication method: Extensible authentication protocol authenticates remote access connection. The authentication mechanism is decided between the remote VPN client and authenticator (ISA). The mechanism is typical in which authenticator requests for authentication information and the responses are given by the remote VPN client. • MS Chap Authentication method: Microsoft Challenge Handshake Authentication Protocol (MS-CHAP) starts with the authenticator (Remote access server) challenge. The challenge to the remote access client sends a session identifier and challenge string. The client in response sends the nonreversible encryption of the string, the identifier and password. Authenticator checks the credentials and grants access on a successful authentication. • Unencrypted passwords (PAP):- Uses plain text passwords. Does not involve encryption. Used for less secure clients. • Shiva Password Authentication Protocol (SPAP):- It is a password authentication protocol. It is less secure as the same user password is always sent in the same reversibly encrypted formWhat is Tunneling?Tunneling is a mechanism provided to transfer data securely between two networks. The data is splitinto smaller packets and passed through the tunnel. The data passing through the tunnel has 3 layersof encryption. The data is encapsulated. Tunneling can be approached by Point to Point tunnelingprotocol.What are voluntary and compulsory tunnels?Voluntary Tunneling - Users computer is an end point of the tunnel and acts as tunnel client. Herethe client or user issues a request to configure and create a voluntary tunnel. They require a dial upor LAN connection. Example of dial up connection is internet at home where a call is made to the ISPand connection is obtained.Compulsory tunneling - In compulsory tunneling, instead of the user a vpn remote access serverconfigures and creates a tunnel. Hence, the end point is the Remote sever not the userExplain static and dynamic tunnels.Tunnels that are created manually are static tunnels. Tunnels that are auto discovered are dynamictunnels. In dynamic tunneling, tcp connections can be checked dynamically. If no connections existthat are routed through the tunnel, a check for more suitable gateway can be done. Static tunnelingmay at times require dedicated equipmentsExplain the importance of increasing and decreasing subnet bits.Adding 1’s as a bit means increasing the subnets and decreasing the hosts. Removing or decreasing1’s means decreasing subnets and increasing hosts. Hence by increasing or decreasing the subnetarchitecture can be decided as per needs
  15. 15. What is RTP?Real-Time Transfer Protocol lays a standard or a way to transfer or manage real time data over anetwork. It does not guarantee the delivery of data or provide any quality of service. However it helpsto manage the data. Which means that RTP can be used deliver the necessary data to the applicationto make sure it can put the received packets in the correct order Real time data examples could beaudio and videoExplain the use of RTP and RTCP protocols.Use of RTP and RTCP:-1. RTP can be used to transfer Real time data like voice packets.2. RTP can be used with RTCP which makes it possible to monitor data.3. Packet loss can be detected by RTP using Sequence numberRTCP provides Qos feedback :- Packets lost, round trip time.Describe the format of RTP and RTCP packets.The 32 bits of RTP packet format is as follows:- (L to R)Bit 0-1:- Indicates version, currently 2Bit 2:- P- indicates padding bytesBit 3:- X- Indicates presence of extension headerBit 4-7:- CC- Contains number of CSRC identifiers that follows the headerBit 8:- M- Current data has some special relevance (if set)Bit 9-15:- PT- Indicates format of payloadBit 16-31:- Sequence numberTimestamp: - 32bits – time stamp of packetSSRC- Synchronization source identifier uniquely identifies the source of a stream.CSRC -Contributing source IDs enumerate contributing sources to a stream which has beengenerated from multiple sourcesExtension header: - first 32 bit word contains profile specific identifier and length specifierThe 32 bits of RTCP header format is as follows:- (L to R)Bit 0-1:- Indicates version, currently 2Bit 2:- P- indicates padding bytesBit 3 to 7:- Count of number of reception report blocksBit 8 to 15:- Type: - Determined RTCP packet type. Type can take values from 0 to 25516 to 31:- Length- Length of RTCP packet - 1SR: - Sender Report for transmission and reception from active sendersRR: - Receiver report for reception from in active sendersSDES: - Source description itemsBYE- indicates end of participationAPP: - Application specific functions
  16. 16. Describe how the multicast protocol works.Multicast protocol or Internet protocol delivers a singles message to multiple machines. One packetfrom the source is replicated and sent to the destination. Every multicast message requires a multicase group. The group defines the addresses which will receive the message. The group is definedby the class D address. Different routing protocols are used to find the multicast groups and buildroutes for them. Distance Vector Multicast protocol is one of them. The receiver, to whom themulticast packet is sent to, needs to ‘join’ the group. Joining the group is enabled and managed byIGMP. Multicast routers are used to transmit the messages from one network to another.Explain why use Multicasting. • When the same message or packet needs to be sent to multiple destinations, multicasting is used. • Within campus and offices, using multicasting file distribution can be done. • System messages, news and videos can be sent at the same time. • More commonly used for audio and video streamingWhat is a socket?A socket is used to connect an application to a network protocol. A socket enables communicationbetween a client and a server. The communication is started when the client is assigned a local portnumber, and binds a socket to it. The client writes on the socket and gets information from server byreading it.What are Sockets? How do Sockets Work?A socket is used to connect an application to a network protocol. A socket enables communicationbetween a client and a server. The communication is started when the client is assigned a local portnumber, and binds a socket to it. The client writes on the socket and gets information from server byreading it. The Socket class is used to communicate. It provides rich set of methods for bothasynchronous and synchronous data transfer. Connect Asynch is used to start an asynchronousconnection. Send Asynch and Receive Asynch are used to send and receive data. Shutdown andclose methods are used to shutdown and close the socketsDatagram vs. stream.Stream can be considered as a pipe that allows full duplex connection. A datagram or a packet on theother hand, has a source and a destination. There is no connection. Stream is like a communicationchannel while datagram is completely self contained. Streams provide a reliable and sequencedcommunication. Datagram’s on the other hand are unreliable and no sequence maintained.
  17. 17. What is a stream socket?A stream socket provides two way communications between a client and server. This communicationis reliable and sequenced. Stream sockets are above TCP to run across any networks. They provideunduplicated flow of data and have well established mechanism for creating and destroyingconnections and for detecting errors.What is SSL?SSL is Secured Socket Layer. SSL is used to establish a secured and an encrypted connectionbetween a server and the browser. SSL is most commonly seen in payment and banking web sites.To create a SSL connection, a SSL certificate needs to be created. If the website has a SSLcertificate installed, a small icon is displayed in the tool bar to make customers confident that the siteis secured.What are the two important TCP Socket classes? Explain themThe two most important socket Classes are: • Socket Class: The Socket class provides enriched methods and properties for network communications. It allows both synchronous and asynchronous data transfer. Shutdown method should be used to end the Socket once the data transfer is complete. Using Set Socket Option the socket can be configured. Declaration : Public Class Socket _Implements ID is possible • Server Socket Class: The server Socket class is used to implement server sockets. Server sockets are used to respond to requests received over the network. S.N.COLLEGE, GADHINGLAJ. Prof- Kodoli R.S