1. Which action is performed by a client when establishing
communication with a server via the use of 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 begin the session.
2. Which transport layer feature is used to guarantee session establishment?
- UDP ACK flag
- TCP 3-way handshake
- UDP sequence number
- TCP port number
3. What is the complete range of TCP and UDP well-known ports?
- 0 to 255
- 0 to 1023
- 256 – 1023
- 1024 – 49151
4. What is a socket?
- the combination of the source and destination IP address and source and destination Ethernet address
- the combination of a source IP address and port number or a destination IP address and port number
- the combination of the source and destination sequence and acknowledgment numbers
- the combination of the source and destination sequence numbers and port numbers
5. A PC is downloading a large file from a server. The TCP
window is 1000 bytes. The server is sending the file using 100-byte
segments. How many segments will the server send before it requires an
acknowledgment from the PC?
- 1 segment
- 10 segments
- 100 segments
- 1000 segments
6. Which factor determines TCP window size?
- the amount of data to be transmitted
- the number of services included in the TCP segment
- the amount of data the destination can process at one time
- the amount of data the source is capable of sending at one time
Explanation: Window
is the number of bytes that the sender will send prior to expecting an
acknowledgement from the destination device. The initial window is
agreed upon during the session startup via the three-way handshake
between source and destination. It is determined by how much data the
destination device of a TCP session is able to accept and process at one
time.
7. What does a client do when it has UDP datagrams to send?
- It just sends the datagrams.
- It queries the server to see if it is ready to receive data.
- It sends a simplified three-way handshake to the server.
- It sends to the server a segment with the SYN flag set to synchronize the conversation.
Explanation: When a client has UDP datagrams to send, it just sends the datagrams.
8. Which three fields are used in a UDP segment header? (Choose three.)
- Window Size
- Length
- Source Port
- Acknowledgment Number
- Checksum
- Sequence Number
Explanation: A UDP
header consists of only the Source Port, Destination Port, Length, and
Checksum fields. Sequence Number, Acknowledgment Number, and Window Size
are TCP header fields.
9. What are two roles of the transport layer in data communication on a network? (Choose two.)
- identifying the proper application for each communication stream
- tracking the individual communication between applications on the source and destination hosts
- providing frame delimiting to identify bits making up a frame
- performing a cyclic redundancy check on the frame for errors
- providing the interface between applications and the underlying network over which messages are transmitted
Explanation: The transport layer has several responsibilities. The primary responsibilities include the following:
- Tracking the individual communication streams between applications on the source and destination hosts
- Segmenting data at the source and reassembling the data at the destination
- Identifying the proper application for each communication stream through the use of port numbers
10. What information is used by TCP to reassemble and reorder received segments?
- port numbers
- sequence numbers
- acknowledgment numbers
- fragment numbers
11. 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
- destination and source physical addresses
- destination and source logical network addresses
12. Which two characteristics are associated with UDP sessions? (Choose two.)
- Destination devices receive traffic with minimal delay.
- Transmitted data segments are tracked.
- Destination devices reassemble messages and pass them to an application.
- Received data is unacknowledged.
- Unacknowledged data packets are retransmitted.
Explanation:
TCP:
- Provides tracking of transmitted data segments
- Destination devices will acknowledge received data.
- Source devices will retransmit unacknowledged data.
UDP
- Destination devices will not acknowledge received data
- Headers use very little overhead and cause minimal delay.
13. A client application needs to terminate a TCP
communication session with a server. Place the termination process steps
in the order that they will occur. (Not all options are used.)
14. Which flag in the TCP header is used in response to a
received FIN in order to terminate connectivity between two network
devices?
15. Which protocol or service uses UDP for a client-to-server communication and TCP for server-to-server communication?
Explanation: Some
applications may use both TCP and UDP. DNS uses UDP when clients send
requests to a DNS server, and TCP when two DNS serves directly
communicate.
16. What is a characteristic of UDP?
- UDP datagrams take the same path and arrive in the correct order at the destination.
- Applications that use UDP are always considered unreliable.
- UDP reassembles the received datagrams in the order they were received.
- UDP only passes data to the network when the destination is ready to receive the data.
Explanation: UDP
has no way to reorder the datagrams into their transmission order, so
UDP simply reassembles the data in the order it was received and
forwards it to the application.
17. What kind of port must be requested from IANA in order to be used with a specific application?
- registered port
- private port
- dynamic port
- source port
Explanation:
Registered ports (numbers 1024 to 49151) are assigned by IANA to a
requesting entity to use with specific processes or applications. These
processes are primarily individual applications that a user has chosen
to install, rather than common applications that would receive a
well-known port number. For example, Cisco has registered port 1985 for
its Hot Standby Routing Protocol (HSRP) process.
18. Which three application layer protocols use TCP? (Choose three.)
- SMTP
- FTP
- SNMP
- HTTP
- TFTP
- DHCP
Explanation: Some
protocols require the reliable data transport that is provided by TCP.
In addition, these protocols do not have real time communication
requirements and can tolerate some data loss while minimizing protocol
overhead. Examples of these protocols are SMTP, FTP, and HTTP.
19. Which three statements characterize UDP? (Choose three.)
- UDP provides basic connectionless transport layer functions.
- UDP provides connection-oriented, fast transport of data at Layer 3.
- UDP relies on application layer protocols for error detection.
- UDP is a low overhead protocol that does not provide sequencing or flow control mechanisms.
- UDP relies on IP for error detection and recovery.
- UDP provides sophisticated flow control mechanisms.
20. Which two fields are included in the TCP header but not in the UDP header? (Choose two.)
- window
- checksum
- source port
- destination port
- sequence number
Explanation: The sequence number and window fields are included in the TCP header but not in the UDP header.
21. Which field in the TCP header indicates the status of the three-way handshake process?
- window
- reserved
- checksum
- control bits
Explanation: The value in the control bits field of theTCP header indicates the progress and status of the connection.
22. 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 be tolerated easily
- because HTTP requires reliable delivery
23. Which two types of applications are best suited for UDP? (Choose two.)
- applications that need data flow control
- applications that require reliable delivery
- applications that handle reliability themselves
- applications that need the reordering of segments
- applications that can tolerate some data loss, but require little or no delay
24. How are port numbers used in the TCP/IP encapsulation process?
- Source port numbers and destination port numbers are not necessary
when UDP is the transport layer protocol being used for the
communication.
- Source port and destination port numbers are randomly generated.
- If multiple conversations
occur that are using the same service, the source port number is used to
track 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 are used to
track different conversations. Destination port numbers identify
specific services by using either a default port number for the service
or a port number that is assigned manually by a system administrator.
25. In what two situations would UDP be better than TCP as the preferred transport protocol? (Choose two.)
- when applications need to guarantee that a packet arrives intact, in sequence, and unduplicated
- when a faster delivery mechanism is needed
- when delivery overhead is not an issue
- when applications do not need to guarantee delivery of the data
- when destination port numbers are dynamic
Explanation: UDP is
a very simple transport layer protocol that does not guarantee
delivery. Devices on both ends of the conversation are not required to
keep track of the conversation. UDP is used as the transport protocol
for applications that need a speedy, best-effort delivery.
26. What are three responsibilities of the transport layer? (Choose three.)
- meeting the reliability requirements of applications, if any
- multiplexing multiple communication streams from many users or applications on the same network
- identifying the applications and services on the client and server that should handle transmitted data
- directing packets towards the destination network
- formatting data into a compatible form for receipt by the destination devices
- conducting error detection of the contents in frames
27. Which three statements describe a DHCP Discover message? (Choose three.)
- The source MAC address is 48 ones (FF-FF-FF-FF-FF-FF).
- The destination IP address is 255.255.255.255.
- The message comes from a server offering an IP address.
- The message comes from a client seeking an IP address.
- All hosts receive the message, but only a DHCP server replies.
- Only the DHCP server receives the message.
Explanation: When a
host configured to use DHCP powers up on a network it sends a
DHCPDISCOVER message. FF-FF-FF-FF-FF-FF is the L2 broadcast address. A
DHCP server replies with a unicast DHCPOFFER message back to the host.
28. Which two protocols may devices use in the application process that sends email? (Choose two.)
- HTTP
- SMTP
- POP
- IMAP
- DNS
- POP3
29. What is true about 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 the FTP protocol for communication.
Explanation: The
Server Message Block protocol is a protocol for file, printer, and
directory sharing. 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. The use of SMB differs from FTP mainly
in the length of the sessions. SMB messages can authenticate sessions.
30. 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
- to upload content to a web server from a web client
- to retrieve client email from an email server using TCP port 110
31. Which OSI layer provides the interface between the
applications used to communicate and the underlying network over which
messages are transmitted?
- application
- presentation
- session
- transport
32. Which networking model is being used when an author uploads one chapter document to a file server of a book publisher?
- peer-to-peer
- master-slave
- client/server
- point-to-point
Explanation: In the
client/server network model, a network device assumes the role of
server in order to provide a particular service such as file transfer
and storage. In the client/server network model, a dedicated server does
not have to be used, but if one is present, the network model being
used is the client/server model. In contrast, a peer-to-peer network
does not have a dedicated server.
33. 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 used only in the wired network environment.
Explanation: In
both the client/server and peer-to-peer network models, clients and
servers exist. In peer-to-peer networks, no dedicated server exists, but
a device can assume the server role to provide information to a device
serving in the client role.
34. In what networking model would eDonkey, eMule, BitTorrent, Bitcoin, and LionShare be used?
- peer-to-peer
- client-based
- master-slave
- point-to-point
Explanation: In a
peer-to-peer networking model, data is exchanged between two network
devices without the use of a dedicated server. Peer-to-peer applications
such as Shareaz, eDonkey, and Bitcoin allow one network device to
assume the role of server, while one or more other network devices
assume the role of client using the peer-to-peer application.
35. What is a common protocol that is used with peer-to-peer applications such as WireShare, Bearshare, and Shareaza?
- Ethernet
- Gnutella
- POP
- SMTP
36. What is a key characteristic of the peer-to-peer networking model?
- wireless networking
- social networking without the Internet
- network printing using a print server
- resource sharing without a dedicated server
Explanation: The peer-to-peer (P2P) networking model allows data, printer, and resource sharing without a dedicated server.
37. The application layer of the TCP/IP model performs the functions of what three layers of the OSI model? (Choose three.)
- physical
- session
- network
- presentation
- data link
- transport
- application
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 equates to the network layer of the OSI model. The transport
layers are the same in both models. The application layer of the TCP/IP
model represents the session, presentation, and application layers of
the OSI model.
38. What is an example of network communication that uses the client-server model?
- A user uses eMule to download a file that is shared by a friend after the file location is determined.
- A workstation initiates an ARP to find the MAC address of a receiving host.
- A user prints a document by using a printer that is attached to a workstation of a coworker.
- A workstation initiates a DNS request when the user types www.cisco.com in the address bar of a web browser.
Explanation: When a
user types a domain name of a website into the address bar of a web
browser, a workstation needs to send a DNS request to the DNS server for
the name resolution process. This request 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.
39. Which layer in the TCP/IP model is used for formatting, compressing, and encrypting data?
- internetwork
- session
- presentation
- application
- 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 the applications, is responsible for formatting,
compressing, and encrypting data, and is used to create and maintain
dialogs between source and destination applications.
40. What is an advantage of SMB over FTP?
- Only with SMB can data transfers occur in both directions.
- Only SMB establishes two simultaneous connections with the client, making the data transfer faster.
- SMB is more reliable than FTP because SMB uses TCP and FTP uses UDP.
- SMB clients can establish a long-term connection to the server.
41. A manufacturing company subscribes to certain hosted
services from its ISP. The services that are required include hosted
world wide web, file transfer, and e-mail. Which protocols represent
these three key applications? (Choose three.)
- FTP
- HTTP
- DNS
- SNMP
- DHCP
- SMTP
42. Which application layer protocol uses message types such as 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.
43. What type 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 mapped to 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 several mail
exchange servers that all belong to the same domain.
44. Which three protocols operate at the application layer of the TCP/IP model? (Choose three.)
- ARP
- TCP
- UDP
- FTP
- POP3
- DHCP
Explanation: FTP,
DHCP, and POP3 are application layer protocols. TCP and UDP are
transport layer protocols. ARP is a network layer protocol.
45. Which 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.
46. Which applications or services allow hosts to act as client and server at the same time?
- client/server applications
- email applications
- P2P applications
- authentication services
47. What are two characteristics of peer-to-peer networks? (Choose two.)
- scalability
- one way data flow
- decentralized resources
- centralized user accounts
- resource sharing without a dedicated server
Explanation:
Peer-to-peer networks have decentralized resources because every
computer can serve as both a server and a client. One computer might
assume the role of server for one transaction while acting as a client
for another transaction. Peer-to-peer networks can share resources among
network devices without the use of a dedicated server.
48. Which scenario describes a function provided by the transport layer?
- A student is using a classroom VoIP phone 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 is playing a short web-based movie with sound. The movie and sound are encoded within the transport layer header.
- A student has two web browser
windows open in order to access two web sites. The transport layer
ensures the correct web page is delivered to the correct browser window.
- A corporate worker is accessing a web server located on a corporate
network. The transport layer formats the screen so the web page appears
properly no matter what device is being used to view the web site.
Explanation: The source and destination port numbers are used to identify the correct application and window within that application.
49. Which three layers of the OSI model provide similar
network services to those provided by the application layer of the
TCP/IP model? (Choose three.)
- physical layer
- session layer
- transport layer
- application layer
- presentation layer
- data link layer
Explanation: The
three upper layers of the OSI model, the session, presentation, and
application layers, provide application services similar to those
provided by the TCP/IP model application layer. Lower layers of the OSI
model are more concerned with data flow.
50. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received two packets of data from the PC?
51. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received three packets of data from the PC?
52. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received four packets of data from the PC?
53. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received four packets of data from the PC?
54. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received two packets of data from the PC?
55. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received two packets of data from the PC?
56. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received two packets of data from the PC?
57. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received two packets of data from the PC?
58. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received three packets of data from the PC?
59. A PC that is communicating with a web server has a TCP
window size of 6,000 bytes when sending data and a packet size of 1,500
bytes. Which byte of information will the web server acknowledge after
it has received three packets of data from the PC?
60. A client creates a packet to send to a server. The client
is requesting TFTP service. What number will be used as the destination
port number in the sending packet?
61. A client creates a packet to send to a server. The client
is requesting FTP service. What number will be used as the destination
port number in the sending packet?
62. A client creates a packet to send to a server. The client
is requesting SSH service. What number will be used as the destination
port number in the sending packet?
63. A client creates a packet to send to a server. The client
is requesting HTTP service. What number will be used as the destination
port number in the sending packet?
64. A client creates a packet to send to a server. The client
is requesting POP3 service. What number will be used as the destination
port number in the sending packet?
65. A client creates a packet to send to a server. The client
is requesting telnet service. What number will be used as the
destination port number in the sending packet?
66. A client creates a packet to send to a server. The client
is requesting POP3 service. What number will be used as the destination
port number in the sending packet?
67. A client creates a packet to send to a server. The client
is requesting SNMP service. What number will be used as the destination
port number in the sending packet?
68. A client creates a packet to send to a server. The client
is requesting SMTP service. What number will be used as the destination
port number in the sending packet?
69. A client creates a packet to send to a server. The client
is requesting HTTPS service. What number will be used as the
destination port number in the sending packet?
0 commentaires:
Enregistrer un commentaire