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CUSTOMER_CODE SMUDE DIVISION_CODE SMUDE EVENT_CODE APR2016 ASSESSMENT_CODE BC0055_APR2016 QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 4255 QUESTION_TEXT List and explain the various phases of LCP? The Link Control Protocol goes through these phases: •Link Establishment and Configuration Negotiation: •Link Quality Determination: SCHEME OF EVALUATION •Authentication: •Network-layer Protocol Configuration Negotiation: •Link Termination: (Each phase with explanation carries 2 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72416 QUESTION_TEXT Explain various attributes of IMAP4 messages. 1. 2. Unique identifier message attribute– (3 Marks) Message sequence number message attribute– SCHEME OF EVALUATION (3 marks) 3. Flags message attribute– (4 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 121861 QUESTION_TEXT Explain generic SNMP traps. SCHEME OF EVALUATION Traps are asynchronous notifications of events occurring within an SNMP community. They can be generated both by SNMP agents and SNMP subagents. at can be RFC architected (called enterprise-specific). Architected traps, defined in RFC 1215, are as follows: 1. coldStartEvent: Notifies managers that the SNMP agent is reinitializing and that the configuration might have been altered. The trap belongs to the RFC1213-archutectured System group, and is therefore supported by SNMP agent. 2. warmStartEvent: Notifies managers that the SNMP agent is reinitializing, but there has been no alteration of the configuration. This trap belongs to the RFC1213-archutectured System group, and is therefore supported by SNMP agent. 3. linkDownEvent: Notifies managers that an interface has been deactivated. Information identifying the interface is included in the trap. This trap belongs to the RFC1213-archutectured Interface group, and is usually supported by a TCP/IP specific subagent. 4. linkUpEvent: Notifies managers that an interface has been activated. Information identifying the interface is included in the trap. This trap belongs to the RFC1213-archutectured Interface group, and is usually supported by a TCP/IP specific subagent. 5. snmpAuthenFailureEvent: Notifies managers that a user attempting to access the SNMP agent. This trap belongs to the RFC1213archutectured SNMP group, and therefore is supported by a SNLP agent. 6. egpNeighborLossEvent: Notifies managers that a relationship with an EGP neighbor no longer exists. Information identifying the EBP neighbor is included in the trap. This trap belongs to the RFC1213archutectured EGP group, and therefore is usually supported by an EGP-specific subagent or a TCP/IP specific-subagent. 7. entSpecificEvent: This trap is a placeholder that allows SNMP agent or subagent implementations to create enterprise-specific traps. Traps generated by an SNMP agent are usually delivered to managers using well known UDP port 162. However, implementations might provide a configuration option to allow traps to be sent to other user-determined ports. If a subagent generates trap, the trap is not sent directly from the subagent to a manager. Instead, the trap is over the DPI condition to the agent, who then sends out the trap to the managers. (10 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 121862 QUESTION_TEXT What is a socket? Give an example. SCHEME OF EVALUATION The socket interface is one of serval application programming interfaces to the communication protocols. Designed to be a generic communication programming interface, socket APIs were first introduced by Berkeley software Distribution (BSD). Although it has not been standardized, Berkeley socket API has become a de facto industry standard abstraction for network TCP/IP socket implementation. Consider the following terminologies: 1. A socket is a special type of file handle, which is used by a process to request network services from the operating system 2. A socket address is the triple: <protocol, local–address, local port> For example, in the TCP/IP I(version 4)suite: <tcp, 192.168.14.234, 8080> 3. A conversation is the communication link between two processes. 4. An association is the 5–tuple that completely specifies the two processes that comprise a connection: <protocol, local–address, local–port, foreign–address, foreign–port> In the TCP/IP (version 4) suite, the following could be a valid association. <tcp, 192.168.14.234, 1500, 192.168.44, 22> 5. A half–association is either one of the following, which each specify half of a connection: <protocol, local–address, local–process> Or: <protocol, foreign–address, foreign–process> QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 121865 QUESTION_TEXT Briefly discuss different application layer protocols SCHEME OF EVALUATION Application Layer: 1. The Hypertext Transfer Protocol(HTTP) transfers fills that make up pages on the world wide web. 2. The File Transfer Protocol (FTP) transfers individual files, typically for an interactive user session. 3. The Simple Mail Transfer Protocol (SMTP) transfers mail messages and attachments. Additionally, the following Application layer protocols help you use and manage TCP/IP networks. 4. The Domain Name System(DNS) protocol resolves a host name, such a www.cisco.com, to an IP address and copies name information between DNS servers. 5. The Routing information Protocol (RIP) is a protocol that routers use to exchange routing information on an IP network. 6. The Simple Network Management Protocol (SNMP) collects and exchanges network management information between a network management console and network devices such as routers, bridges and servers. 7. Windows Sockets and NetBIOS are examples of Application layer interfaces for TCP/IP application. QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 121866 QUESTION_TEXT Explain various steps involved in SMTP mail transaction flow. 1. 2. 3. 4. 5. SCHEME OF EVALUATION 6. 7. The sender SMTP establishes a TCP connection with the destination SMTP and then waits for the server to send a 220 Service ready message or 421 service not available message when the destination is temporarily unable to proceed. HELO is sent to which the receiver will identify itself by sending back its domain name……………………………that it supports. The sender now initiates the start of a mail transaction by sending a MAIL command to the receiver…………………….the receiver replies with a 250 OK. The second step of the actual mail exchange consists of providing the server SMTP with the destinations for the message…….. When all RCPT commands are sent, the sender issues a DATA command to notify the receiver that the message contents will follow………..sender should use to terminate the message data. The client now sends the data line by line, ending with the 5character sequence………..went wrong At this junction, the client now has several possible actions * If the sender has no more messages to send, but it can end the connection with a QUIT command * If the sender has no more messages to send, but is ready to receive messages from the other side. * If the sender has another message to send, it returns to step 3 and sends a new MAIL command.