Cisco CCENT/CCNA ICND1 100-101 Chapter 5

What is the correct sequence for TCP connection establishment? A. There is no sequence because TCP is a connectionless protocol. B. (1) ACK (2) SYN ACK (3) SYN C. (1) SYN (2) SYN ACK (3) ACK D. (1) SYN (2) ACK (3) SYN

(1) SYN (2) SYN ACK (3) ACK TCP uses a three-way connection establishment flow that must be completed before data transfer can begin. SYN means synchronize the sequence numbers, and ACK means that the acknowledgment field is valid in this header.

What is Connectionless protocol?

A protocol that does not require an exchange of messages and that does not require a preestablished correlation between two endpoints.

What is Connection-oriented protocol?

A protocol that requires an exchange of messages before data transfer begins, or that has a required preestablished correlation between two endpoints

What are the four competing characteristics of QoS?

Bandwidth Delay Jitter Loss

What are the advantages of UDP?

By providing fewer services, UDP needs fewer bytes in its header compared to TCP, resulting in fewer bytes of overhead in the network. UDP software does not slow down data transfer in cases where TCP can purposefully slow down.

What are the two types of connection protocols?

Connection-oriented protocol Connectionless protocol

What protocol does User Datagram Protocol (UDP) use?

Connectionless protocol

What is Ordered data transfer and data segmentation?

Continuous stream of bytes from an upper-layer process that is "segmented" for transmission and delivered to upper-layer processes at the receiving device, with the bytes in the same order.

Which of the following is not a feature of a protocol that is considered to match OSI Layer 4? A. Conversion from binary to ASCII B. Flow control C. Segmenting of application data D. Error recovery

Conversion from binary to ASCII Three of the answers define functions of TCP: error recovery, flow control, and segmentation. The correct answer defines a function not done by TCP nor UDP, but instead done by application layer protocols.

Which of the following answers lists the correct layer 4 protocol(s) and well-known port used by each application? A. DNS: UDP and TCP, port 53 B. POP3: UDP, 110 C. HTTP: TCP, port 110 D. SSH: TCP, port 22 Select 2 answers.

DNS: UDP and TCP, port 53 SSH: TCP, port 22 SSH uses TCP well-known port 22. POP3 uses TCP well-known port 110. DNS uses both TCP and UDP, for different purposes, in both cases with well-known port 53. HTTP uses TCP well-known port 80.

Data applications have different QoS requirements, how is this determine?

Depending on whether they are interactive or batch.

What is Multiplexing using ports?

Function that allows receiving hosts to choose the correct application for which the data is destined, based on the port number

An internetwork supports traditional data applications such as web, file transfer, and chat, as well as Voice over IP (VoIP) and Video over IP. Which of the following two statements are most accurate about the impact of these applications on the internetwork? A. Chat typically requires lower delay than video over IP. B. If all types of traffic experience high jitter, data applications tend to work better than VoIP and video over IP. C. VoIP traffic needs low delay and low jitter but can tolerate more packet loss than web applications. D. A single VoIP call tends to take less bandwidth than a single videoconference. Select 2 answers.

If all types of traffic experience high jitter, data applications tend to work better than VoIP and video over IP. A single VoIP call tends to take less bandwidth than a single videoconference. VoIP traffic typically requires low bandwidth but requires low delay and low jitter (variation in delay) and prefers little or no packet loss. Two-way video has the same requirements, but it generates much more traffic. Web applications use HTTP, which uses TCP, which in turn can recover from lost packets.

What do you call data that includes the Layer 4 protocol header, and data given to Layer 4 by the upper layers, not including any headers and trailers from Layers 1 to 3? A. Packet B. Frame C. L4PDU D. Segment E. Chunk F. L3PDU Select 2 answers.

L4PDU Segment The terms packet and L3PDU refer to the header plus data encapsulated by Layer 3. Frame and L2PDU refer to the header (and trailer), plus the data encapsulated by Layer 2. Segment and L4PDU refer to header and data encapsulated by the transport layer protocol.

Which of the following functions is performed by both TCP and UDP? A. Multiplexing using port numbers B. Windowing C. Error recovery D. Ordered data transfer E. Encryption F. Routing

Multiplexing using port numbers TCP, not UDP, performs windowing, error recovery, and ordered data transfer. Neither performs routing or encryption.

Which of the following are typical functions of TCP? A. Multiplexing using port numbers B. Routing C. Encryption D. Ordered data transfer E. Flow Control (windowing) F. Error recovery Select 4 answers

Multiplexing using port numbers Ordered data transfer Flow Control (windowing) Error recovery IP, not TCP, defines routing. Many other protocols define encryption, but TCP does not. The correct answers simply list various TCP features.

What are some of TCP/IP Transport Layer Features?

Multiplexing using ports Error recovery (reliability) Flow control using windowing Connection establishment and termination Ordered data transfer and data segmentation

What is a vital part of the socket concept?

Port numbers

What is Error recovery (reliability) ?

Process of numbering and acknowledging data with Sequence and Acknowledgment header fields.

What is Flow control using windowing?

Process that uses window sizes to protect buffer space and routing devices from being overloaded with traffic.

What is Connection establishment and termination?

Process used to initialize port numbers and Sequence and Acknowledgment fields

What is qualities as quality of service (QoS)?

QoS in general defines the quality of the data transfer between two applications and in the network as a whole.

What is the key difference between TCP and UDP?

TCP provides a wide variety of services to applications, whereas UDP does not

A user in an Enterprise network sits at her PC and connects to a web server inside the Enterprise by entering the URL http://www.example.com/payroll.html into the browser's window and pressing Enter. Which of the following answers are true about the actions taken by the user's PC? A. The PC uses Hypertext Transfer Protocol (HTTP) to get the files that comprise the requested web page. B. All the text after the // in the URL (in the question) is considered to be the server's hostname and is used in the DNS request to find the server's IP address. C. The user's action of entering the URL and pressing Enter may result in multiple HTTP get requests being made to the server. D. If any packets sent by the server are lost in transit, HTTP causes the server to resend the lost data. Select 2 answers.

The PC uses Hypertext Transfer Protocol (HTTP) to get the files that comprise the requested web page. The user's action of entering the URL and pressing Enter may result in multiple HTTP get requests being made to the server. Web browsers use HTTP, which in turn uses TCP. The web browser connects to the server with a TCP connection and issues a get request to get the first file in the web page. That object may include instructions to load additional files (objects), again with HTTP get requests. The hostname that identifies the server is located between the double slash (//) and the single slash (/) in the URL; the text after the single slash identifies the web page on that particular server.

What is Delay?

The amount of time it takes one IP packet to flow from sender to receiver.

The TCP connection exists between how many sockets?

The connection exists between the two sockets, although the TCP header has no single socket field.

What is Loss?

The percentage of packets discarded by the network before they reach the destination, which when using TCP, requires a retransmission.

What are the only parts of the socket that need to be encoded in the TCP header?

The port numbers

What is Connection establishment?

The process of initializing sequence and acknowledgment fields and agreeing on the port numbers used.

Of the three parts of a socket, the IP addresses are implied based on what?

The source and destination IP addresses in the IP header.

A user sits at her PC at her desk inside an Enterprise network. She opens a web browser and connects to a website that sits on the Internet. Which of the following answers is most true about the applications and functions used as a result of this user's actions? A. The transfer of files uses the FTP protocol. B. The user's PC sends at least two messages to the server before requesting the specific web page. C. UDP is used as part of the process of resolving the website's name into the default gateway's MAC address. D. UDP is used as part of the process of transferring files from the web server to the user's web browser.

The user's PC sends at least two messages to the server before requesting the specific web page. Web browsers connect to web servers by referencing the URI of the web server. The client must find the hostname part of the URI and then find the IP address (not the MAC address) used by the server, typically by using a DNS request. The browser then uses HTTP to get the contents of the web page, with HTTP using TCP. The browser must initiate a TCP connection to the server, which requires a three-way initialization handshake, with two of those messages going from the user's PC to the server.

What is Jitter?

The variation in delay.

What is Bandwidth?

The volume of bits per second needed for the application to work well; it can be biased with more volume in one direction, or balanced.

what is Batch applications?

They focus more on the bandwidth between two software processes. Batch applications often do not even have a human in the picture.

What is Interactive data applications?

This usually has a human user at one end of a flow, and the IP packets must flow in both directions for meaningful work to happen.

What must complete in Connection establishment before data transfer can begin?

Three-way connection establishment flow (also called a three-way handshake)

What protocol does DNS use to transfer data?

UDP

Which of the following header fields identify which TCP/IP application gets data received by the computer? A. UDP Port Number B. IP Protocol C. SNAP Protocol Type D. Ethernet Type E. TCP Port Number Select 2 answers

UDP Port Number TCP Port Number Many headers include a field that identifies the next header that follows inside a message. Ethernet uses the Ethernet Type field, and the IP header uses the Protocol field. The TCP and UDP headers identify the application that should receive the data that follows the TCP or UDP header by using the port number field in the TCP and UDP headers, respectively.

Which of the following are characteristics of UDP? A. UDP is at the Transport layer. B. UDP is connectionless. C. UDP is unreliable. D. UDP uses no acknowledgments. E. UDP is used with TFTP. F. UDP is connection-oriented. Select 5 answers.

UDP is at the Transport layer. UDP is connectionless. UDP is unreliable. UDP uses no acknowledgments. UDP is used with TFTP. UDP sends packets blind down the network and relies on upper-layer protocols to form connections and detect errors. TCP is a connection-oriented protocol that can provide reliable transport.

When comparing VoIP with an HTTP-based mission-critical business application, which of the following statements are accurate about the quality of service needed from the network? A. HTTP needs less bandwidth. B. VoIP needs better (lower) delay C. HTTP needs better (lower) jitter. D. VoIP needs better (lower) packet loss. Select 2 answers.

VoIP needs better (lower) delay VoIP needs better (lower) packet loss. VoIP flows need better delay, jitter, and loss, with better meaning less delay, jitter, and loss, as compared with all data applications. VoIP typically requires less bandwidth than data applications.

UDP provides some functions of TCP, what are they?

data transfer multiplexing using port numbers does so with fewer bytes of overhead and less processing required than TCP

What are some of the important functions of the OSI Transport Layer (Layer 4)

error recovery and flow control

Give some examples of what TCP provides.

reliability windowing reordering of the received data segmentationof large chunks of data into the right size for transmission

What concept does Multiplexing relies on?

socket

What does the UDP header contain?

source and destination port fields, UDP has only 8 bytes, in comparison to the 20-byte TCP header

In the URL http://www.certskills.com/ICND1, which part identifies the web server? A. http://www.certskills.com B. www.certskills.com C. http D. certskills.com E. The file name.html includes the host name.

www.certskills.com Note that the host name is all the text between the // and the /. The text before the // identifies the application layer protocol, and the text after the / represents the name of the web page

What three things a socket consist of?

■ An IP address ■ A transport protocol ■ A port number

What are the three parts of a URL?

■ The protocol is listed before the //. ■ The host name is listed between the // and the /. ■ The name of the web page is listed after the /.