Modules 14-15: Network Application Communications Exam - ITN (Version 7.00) - Network Application Communications Exam Answers
1. What kind of information is contained in a DNS MX record?
- the FQDN of the alias used to identify a service
- the IP address for an FQDN entry
- the domain name associated with Mail Exchange servers
- the IP address of an authoritative name server
Explanation:MX or mail exchange messages are used to map a domain name to multiple mail exchange servers that all belong to the same domain.
2. What three protocols work at the application layer of the TCP/IP model? (Choose three.)
Explanation:FTP, DHCP and POP3 are application layer protocols. TCP and UDP are transport layer protocols. ARP is a network layer protocol.
3. What protocol is used by a client to communicate securely with a web server?
Explanation:HTTPS is a secure form of HTTP used to access web content hosted by a web server.
4. What applications or services enable hosts to act as client and server at the same time?
- Client/Server Applications
- Email Applications
- P2P applications
- authentication services
Explanation:P2P applications allow clients to behave as servers when needed. When using authentication services, e-mail exchanges and client/server applications, one host always acts as a server and the other as a client.
5. What are two characteristics of peer-to-peer networks? (Choose two.)
- One-way data flow
- decentralized resources
- centralized user accounts
- sharing resources without a dedicated server
Explanation:Peer-to-peer networks have decentralized resources because each computer can serve as both a server and a client. A computer can act as a server for one transaction while acting as a client for another transaction. Peer-to-peer networks can share resources between network devices without using a dedicated server.
6. Which scenario describes a function provided by the transport layer?
- A student uses a VoIP phone in the classroom to call home. The unique identifier burned into the phone is a transport layer address used to contact another network device on the same network.
- A student plays a short web-based movie with sound. The movie and sound are encoded in the transport layer header.
- A student opened two web browser windows to access two websites. The transport layer ensures that the correct web page is delivered to the correct browser window.
- A company employee accesses a web server located on a company network. The transport layer formats the screen so that the webpage is displayed correctly, no matter what device is used to view the website.
Explanation:The source and destination port numbers are used to identify the correct application and window within that application.
7. Which three layers of the OSI model provide network services similar to the application layer of the TCP/IP model? (Choose three.)
- physical layer
- session layer
- transport layer
- application layer
- presentation slide
- data transmission level
Explanation:The top three layers of the OSI model, the session, presentation, and application layers, provide application services similar to those provided by the application layer of the TCP/IP model. Lower layers of the OSI model are more concerned with data flow.
8. A PC communicating with a web server has a TCP window size of 6,000 bytes and a packet size of 1,500 bytes when sending data. What byte of information will the web server report back after receiving two packets of data from the PC?
9. In which network model would eDonkey, eMule, BitTorrent, Bitcoin and LionShare be used?
- Client based
- point to point
Explanation:In a peer-to-peer network model, data is exchanged between two network devices without using a dedicated server. Peer-to-peer applications such as Shareaz, eDonkey, and Bitcoin allow one network device to take on the role of the server while one or more other network devices take on the role of the client using the peer-to-peer application.
10. What is a common protocol used with peer-to-peer applications like WireShare, Bearshare and Shareaza?
Explanation:The Gnutella protocol is used when a user shares an entire file with another user. A person would load a Gnutella-based application such as gtk-gnutella or WireShare and use that application to find and access resources shared by others.
11. What is a key feature of the peer-to-peer network model?
- Wireless networking
- Social networks without internet
- Network printing via a print server
- sharing resources without a dedicated server
Explanation:The peer-to-peer (P2P) network model allows data, printers and resources to be shared without a dedicated server
12. The application layer of the TCP/IP model performs the functions of which three layers of the OSI model? (Choose three.)
- Data Connection
Explanation:The network access layer of the TCP/IP model performs the same functions as the physical and data link layers of the OSI model. The internetwork layer corresponds to the network layer of the OSI model. The transport layers are the same for both models. The application layer of the TCP/IP model represents the session, presentation, and application layers of the OSI model
13. What is an example of network communication using the client-server model?
- A user uses eMule to download a file shared by a friend after determining the file's location.
- A workstation initiates an ARP to find the MAC address of a receiving host.
- A user prints a document using a printer attached to a colleague's workstation.
- A workstation initiates a DNS request when the user types www.cisco.com in a web browser's address bar.
Explanation:When a user types a website's domain name into a web browser's address bar, a workstation must send a DNS query to the DNS server for the name resolution process. This requirement is a client/server model application. The eMule application is P2P. Sharing a printer on a workstation is a peer-to-peer network. Using ARP is just a broadcast message sent by a host.
14. What layer in the TCP/IP model is used to format, compress, and encrypt data?
- Internet work
- network access
Explanation:The application layer of the TCP/IP model performs the functions of three layers of the OSI model - application, presentation and session. The application layer of the TCP/IP model is the layer that provides the interface between applications, is responsible for formatting, compressing, and encrypting data, and is used to create and manage dialogs between source and target applications.
15. What is an advantage of SMB over FTP?
- Only SMB can transfer data in both directions.
- Only SMB establishes two simultaneous connections with the client, which makes data transfer faster
- SMB is more reliable than FTP because SMB uses TCP and FTP uses UDP
- SMB clients can establish a permanent connection to the server
16. A manufacturing company subscribes to certain hosted services from its ISP. Required services include hosted World Wide Web, file transfer, and email. Which protocols do these three main applications represent? (Choose three.)
Explanation:The ISP uses the HTTP protocol in connection with hosting websites, the FTP protocol with file transfers, and SMTP with email. DNS is used to translate domain names into IP addresses. SNMP is used for network management traffic. DHCP ic is commonly used to manage IP addressing.
17. Which application layer protocol uses message types like GET, PUT and POST?
Explanation:The GET command is a client request for data from a web server. A PUT command uploads resources and content, such as images, to a web server. A POST command uploads data files to a web server.
18. What action is taken by a client when it establishes communication with a server using UDP at the transport layer?
- The client sets the window size for the session.
- The client sends an ISN to the server to start the 3-way handshake.
- The client randomly selects a source port number.
- The client sends a synchronization segment to start the session.
19. What transport layer function is used to ensure session establishment?
20. What is the full range of well-known TCP and UDP ports?
- 0 bis 255
- 0 bis 1023
- 256 – 1023
- 1024 – 49151
21. What is a socket?
- the combination of source and destination IP address and source and destination Ethernet address
- the combination of source IP address and port number or destination IP address and port number
- the combination of source and destination sequence and confirmation numbers
- the combination of source and destination sequence numbers and port numbers
22. A PC downloads a large file from a server. The TCP window is 1000 bytes. The server sends the file in 100 byte segments. How many segments does the server send before it needs an acknowledgment from the PC?
- 1 Segment
- 10 Segments
- 100 Segments
- 1000 Segments
Explanation:With a 1000 byte window, the target host will accept segments until all 1000 bytes of data have been received. Then the target host sends an acknowledgment.
23. What factor determines the TCP window size?
- the amount of data to be transferred
- the number of services contained in the TCP segment
- the amount of data that the target can process at one time
- the amount of data that the source can send at one time
Explanation:Window is the number of bytes the sender sends before expecting an acknowledgment from the target device. The initial window is negotiated during session start via the three-way handshake between source and destination. It is determined by how much data the target device of a TCP session can accept and process at the same time.
24. What does a client do when it needs to send UDP datagrams?
- It only sends the datagrams.
- It queries the server if it is ready to receive data.
- It sends a simplified three-way handshake to the server.
- It sends a segment with the SYN flag set to the server to synchronize the conversation.
Explanation:When a client has UDP datagrams to send, it simply sends the datagrams.
25. What three fields are used in a UDP segment header? (Choose three.)
- window size
- confirmation number
- sequence number
Explanation:A UDP header consists only of the Source Port, Destination Port, Length and Checksum fields. Sequence Number, Acknowledgment Number, and Window Size are TCP header fields.
26. What are the two roles of the transport layer in data communication in a network? (Choose two.)
- Identifying the right application for each communication stream
- Trace individual communication between applications on the source and destination hosts
- providing a frame boundary to identify bits that make up a frame
- Performing a cyclic redundancy check of the frame for errors
- Providing the interface between applications and the underlying network over which messages travel
Explanation:The transport layer has several tasks. The main tasks include:
- Trace each communication stream between applications on the source and destination hosts
- Segment data at the source and reassemble it at the destination
- Identifying the correct application for each communication stream through the use of port numbers
27. What information does TCP use to reassemble and reorder received segments?
- port numbers
- sequence numbers
- confirmation numbers
- fragment numbers
Explanation:At the transport layer, TCP uses the sequence numbers in the header of each TCP segment to reassemble the segments in the correct order.
28. What important information is added to the TCP/IP transport layer header to ensure communication and connectivity with a remote network device?
- timing and synchronization
- destination and source port numbers
- physical destination and source addresses
- logical destination and source network addresses
29. What two characteristics are associated with UDP sessions? (Choose two.)
- Target devices receive traffic with minimal delay.
- Transmitted data segments are tracked.
- Target devices reassemble messages and forward them to an application.
- Received data is not confirmed.
- Unacknowledged data packets are retransmitted.
- Provides tracking of transmitted data segments
- Target devices will acknowledge received data.
- Source devices retransmit unacknowledged data.
- Target devices will not acknowledge received data
- Headers consume very little overhead and introduce minimal delays
30. A client application must end a TCP communication session with a server. Arrange the steps of the termination process in the order in which they are performed. (Not all options are used.)
Explanation:To end a TCP session, the client sends a segment with the FIN flag set to the server. The server acknowledges the client by sending a segment with the ACK flag set. The server sends a FIN to the client to end the server-to-client session. The client acknowledges completion by sending a segment with the ACK flag set.
31. Which flag in the TCP header is used in response to a received FIN to terminate connectivity between two network devices?
Explanation:When a device has no more data to send in a TCP session, it sends a segment with the FIN flag set. The connected device receiving the segment responds with an ACK to acknowledge that segment. The device that sent the ACK then sends a FIN message to close the connection it has with the other device. Sending the FIN should be followed by receiving an ACK from the other device
32. Which protocol or service uses UDP for client-to-server communication and TCP for server-to-server communication?
Explanation:Some applications can use both TCP and UDP. DNS uses UDP when clients send queries to a DNS server and TCP when two DNS servers communicate directly.
33. What is a property of UDP?
- UDP datagrams take the same path and arrive at the destination in the correct order
- Applications using UDP are always considered unreliable
- UDP reassembles the received datagrams in the order in which they were received.
- UDP only submits data to the network when the destination is ready to receive the data.
Explanation:UDP has no way of reordering the datagrams in their transmission order, so UDP simply reassembles the data in the order it was received and forwards it to the application
34. A PC communicating with a web server has a TCP window size of 6,000 bytes and a packet size of 1,500 bytes when sending data. What byte of information will the web server report back after receiving three packets of data from the PC?
35. A PC communicating with a web server has a TCP window size of 6,000 bytes and a packet size of 1,500 bytes when sending data. What byte of information will the web server report back after receiving four packets of data from the PC?
36. A client creates a packet to be sent to a server. The client requests the TFTP service. What number is used as the destination port number in the sending packet?
37. A client creates a packet to be sent to a server. The client requests the FTP service. What number is used as the destination port number in the sending packet?
38. A client creates a packet to be sent to a server. The client requests the SSH service. What number is used as the destination port number in the sending packet?
39. A client creates a packet to be sent to a server. The client requests the HTTP service. What number is used as the destination port number in the sending packet?
40. A client creates a packet to be sent to a server. The client requests the POP3 service. What number is used as the destination port number in the sending packet?
41. A client creates a packet to be sent to a server. The client requests the telnet service. What number is used as the destination port number in the sending packet?
42. A client creates a packet to be sent to a server. The client requests the SNMP service. What number is used as the destination port number in the sending packet?
43. A client creates a packet to be sent to a server. The client requests the SMTP service. What number is used as the destination port number in the sending packet?
44. A client creates a packet to be sent to a server. The client requests the HTTPS service. What number is used as the destination port number in the sending packet?
45. Which field in the TCP header indicates the status of the three-way handshake process?
- control bits
Explanation:The value in the control bits field of the TCP header indicates the progress and status of the connection.
46. Why does HTTP use TCP as the transport layer protocol?
- to ensure the fastest possible download speed
- because HTTP is a best effort protocol
- because transmission errors can easily be tolerated
- because HTTP requires reliable delivery
Explanation:When a host requests a web page, transmission security and integrity must be guaranteed. Therefore, HTTP uses TCP as the transport layer protocol.
47. Which two types of applications are best suited for UDP? (Choose two.)
- Applications that require data flow control
- Applications that require reliable delivery
- Applications that take care of reliability themselves
- Applications that require segment reordering
- Applications that can tolerate some data loss but require little or no delay
48. How are port numbers used in the TCP/IP encapsulation process?
- Source port numbers and destination port numbers are not required when UDP is the transport layer protocol used for communication.
- Source port and destination port numbers are randomly generated.
- When multiple conversations are taking place using the same service, the source port number is used to keep track of the separate conversations.
- Destination port numbers are assigned automatically and cannot be changed.
Explanation:Both UDP and TCP use port numbers to provide a unique identifier for each conversation. Source port numbers are randomly generated and used to track various conversations. Destination port numbers identify specific services using either a default port number for the service or a port number manually assigned by a system administrator.
49. In what two situations would UDP be the preferred transport protocol over TCP? (Choose two.)
- when applications need to guarantee that a packet arrives intact, sequential, and non-duplicate
- when a faster delivery mechanism is needed
- if delivery costs are not an issue
- when applications do not have to guarantee the delivery of the data
- if destination port numbers are dynamic
Explanation:UDP is a very simple transport layer protocol that does not guarantee delivery. Devices at both ends of the conversation are not required to track the conversation. UDP is used as a transport protocol for applications that require fast and best possible delivery.
50. What are the three tasks of the transport layer? (Choose three.)
- Meeting the reliability requirements of applications, if any
- Multiplexing of multiple communication streams from many users or applications on the same network
- Identifying the applications and services on the client and server that should process transmitted data
- Forward packets to the destination network
- Format data into a compatible form for reception by target devices
- Perform error detection of the content in frames
Explanation:The transport layer has several tasks. Some of the main tasks include the following:
Trace each communication stream between applications on the source and destination hosts
Segment data at the source and reassemble it at the destination
Identifying the correct application for each communication stream through the use of port numbers
Multiplexing of communications from multiple users or applications over a single network
Manage application reliability requirements
51. Which three statements describe a DHCP Discover message? (Choose three.)
- The source MAC address consists of 48 ones (FF-FF-FF-FF-FF-FF).
- The destination IP address is 255.255.255.255.
- The message comes from a server that offers an IP address.
- The message is from a client looking for an IP address.
- All hosts get the message, but only one DHCP server responds.
- Only the DHCP server receives the message.
Explanation:When a host configured to use DHCP boots up on a network, it sends a DHCPDISCOVER message. FF-FF-FF-FF-FF-FF is the L2 broadcast address. A DHCP server responds back to the host with a unicast DHCPOFFER message.
52. What two protocols are devices allowed to use in the application process that sends email? (Choose two.)
Explanation:POP, POP3, and IMAP are protocols used to retrieve email from servers. SMTP is the standard protocol used to send emails. DNS can be used by the sender email server to find the address of the destination email server.
53. What is the Server Message Block Protocol?
- Different SMB message types have a different format.
- Clients establish a long-term connection to servers.
- SMB messages cannot authenticate a session.
- SMB uses FTP protocol for communication.
Explanation:The Server Message Block protocol is a file, printer, and directory sharing protocol. Clients establish a long-term connection to servers, and when the connection is active, the resources can be accessed. Every SMB message has the same format. Using SMB differs from FTP mainly in the length of the sessions. SMB messages can authenticate sessions.
54. What is the function of the HTTP GET message?
- to request an HTML page from a web server
- to send error information from a web server to a web client
- Upload content from a web client to a web server
- for retrieving client emails from an email server over TCP port 110
55. Which OSI layer forms the interface between the applications used for communication and the underlying network over which the messages are transmitted?
56. What network model is used when an author uploads a chapter document to a book publisher's file server?
- customer server
- point to point
Explanation:In the client/server network model, a network device takes on the role of a server to provide a specific service such as file transfer and storage. The client/server network model does not require the use of a dedicated server, but if one is present, the network model used is the client/server model. In contrast, a peer-to-peer network does not have a dedicated server.
57. What do the client/server and peer-to-peer network models have in common?
- Both models have dedicated servers.
- Both models support devices in server and client roles.
- Both models require the use of TCP/IP based protocols.
- Both models are only used in the wired network environment.
Explanation:Clients and servers exist in both client/server and peer-to-peer network models. A dedicated server does not exist in peer-to-peer networks, but a device can assume the server role to deliver information to a device serving in the client role.
58. What type of port needs to be requested from the IANA to be used with a specific application?
- registered port
- private port
- Dynamic port
Explanation:Registered ports (numbers 1024 through 49151) are assigned by the IANA to a requestor for use with specific processes or applications. These processes are primarily individual applications that a user chose to install, rather than general applications that would be given a known port number. For example, Cisco registered port 1985 for its Hot Standby Routing Protocol (HSRP) process
59. Which three application layer protocols use TCP? (Choose three.)
Explanation:Some protocols require the reliable data transport provided by TCP. Also, these protocols have no real-time communication requirements and can tolerate some data loss while minimizing protocol overhead. Examples of these protocols are SMTP, FTP and HTTP.
60. Which three statements characterize UDP? (Choose three.)
- UDP provides basic connectionless transport layer functionality.
- UDP offers a connection-oriented, fast data transport on layer 3.
- UDP relies on application layer protocols for error detection.
- UDP is a low-overhead protocol that does not provide any sequencing or flow control mechanisms.
- UDP relies on IP for error detection and recovery.
- UDP offers sophisticated flow control mechanisms.
Explanation:UDP is a simple protocol that provides the basic transport layer functions. It has a much lower overhead than TCP because it is not connection-oriented and does not offer the sophisticated transmission, sequencing, and flow control mechanisms that ensure reliability.
61. What two fields are in the TCP header but not in the UDP header? (Choose two.)
- destination port
- sequence number
Explanation:The sequence number and window fields are included in the TCP header but not in the UDP header.