Final Exam IT 276 Data Communication
What follows is a fill in the blank question with 1 blanks. as an example of Transport protocol that is connectionless
UDP
YouTube is a network application. True False
True
A problem with the star topology is that one cannot add or remove hosts without shutting down the entire network. True False
false
The OSI model has 6 layers. True False
false
The TCP/IP protocol suite was designed in 1970s by 2 DARPA scientists—Vint Cerf and Bob Kahn. They are most often called the fathers of the Internet. True False
True
The bit ACK is needed both in the phase of establishing a TCP connection and in the phase of closing that connection. True False
True
To communicate with a Web server, a broswser uses a language called HTTP (Hypertext Transfer Protocol). True False
True
Match the following: A. Graphical web browser B. Operating systems C. American social media application D. Photo and video-sharing Application E. Cross-platform web browser 1. Google Chrome 2. Safari 3. Window 10 4. Facebook 5. Instagram
1. Google Chrome - E 2. Safari - A 3. Window 10-B 4. Facebook-C 5. Instagram-D
Match the following A. Standard B. Transport Layer Address C. Data Link Layer address D. Protocol E. Network Layer address select A B C D E 1. HTTP select A B C D E 2. HTML select A B C D E 3. IP address select A B C D E 4. Port Address select A B C D E 5. Mac Address
1. HTTP-D 2. HTML-A 3. IP address-E 4. Port Address-B 5. Mac Address-C
Match the traffic description in different layers of the TCP/IP Model using the following: A. Message B. Bits C. Packet D. Segment E. Frame select A B C D E 1. Transport Layer select A B C D E 2. Network Layer select A B C D E 3. Data Link Layer select A B C D E 4. Application Layer select A B C D E 5. Physical Layer
1. Transport Layer-D 2. Network Layer-C 3. Data Link Layer- E 4. Application Layer- A 5. Physical Layer- B
Match the following of OSI Model with correct answers: A. Addressing, routing, message delivery across networks B. Establishes & manages sessions between hosts C. Reliability, flow control, error control D. User interaction with software program E. Data formatting, compression, and encryption 1. Application Layer 2. Presentation Layer 3. Session Layer 4. Transport Layer 5. Network Layer
1:D, 2:E, 3:B, 4:C, 5:A
Socket has A. IP address plus port number B. Indicates specific NICK card in specific machine C. Not every networked application on every host uses the socket for the application to communicate with other applications on other hosts D. IP address + port address + MAC address
A. IP address plus port number
SMTP uses the following except: A. persistent connections B. UDP to transfer email message from client to server C. port 25 D. direct transfer: sending server to receiving server E. SMTP requires message (header & body) to be in 7-bit ASCII
B. UDP to transfer email message from client to server
SSL provides the following except : A. provides encrypted TCP connection B. data integrity C. Maximum Throughput D. end-point authentication
C. Maximum Throughput
In TCP: A. a lost segment is resent by the sender only if the receiver requested B. Each segment is resent automatically after the timer is expired C. Sender keep a copy of segment that he sent until the sender received acknowledgment from the receiver. D. Lost segment will be replaced by default segment created by the sender
C. Sender keep a copy of segment that he sent until the sender received acknowledgment from the receiver.
The minimum needed for a network or components of data communication system are the following except: A. At least two computers B. Shared media C. Standard to unify the system D. Shared protocol ("language") E. Data to transmit (message)
C. Standard to unify the system
FTP client: A. contacts FTP server at port 20 B. using UDP as the transport protocol C. client authorized over control connection channel D. client browses remote directory using 2nd UDP connection (for file) to server as data connection on port 22.
C. client authorized over control connection channel
protocol defines the following except: types of messages exchanged, e.g., request, response message syntax: what fields in messages & how fields are delineated message semantics meaning of information in fields rules for when and how processes send & respond to messages A. message syntax: what fields in messages & how fields are delineated B. message semantics meaning of information in fields C. round trip and processing delays D. rules for when and how processes send & respond to messages
C. round trip and processing delays
Layering advantages include all the following except: A. Allows specialization in design B. Allows easier troubleshooting C. Replacement of a protocol at one layer is easier D. A protocol at one layer must understand all layers above and below.
D. A protocol at one layer must understand all layers above and below
TCP handshaking is needed: A. only when you send HTTP message B. Only when you send TFTP message C. Only when you send SMTP D. Before TCP sending any application data to any destination
D. Before TCP sending any application data to any destination
SFTP is Just like FTP except: A. uses two channels for both control and data B. client contacts FTP server at port 21 C. using UDP transport protocol D. Data is encrypted and authenticate both the user and server
D. Data is encrypted and authenticate both the user and server
TCP Handshakes include the following except: A. One side sends a TCP segment with the SYN flag set B. Other side replies with a segment with both SYN and ACK set C. Original sender replies with a segment with ACK set D. Finally the sender side send test segment with multiple SYN to test the link
D. Finally the sender side send test segment with multiple SYN to test the link
TCP segment has the following except: A. Application data B. Source Port address C. Destination Port address D. Source and destination IP addresses
D. Source and destination IP addresses
Application protocols are defined by the following except: A. Types of messages exchanged, e.g., request, response B. message syntax, what fields in messages & how fields are delineated C. message semantics, meaning of information in fields D. address to identify the ID of the sender E. rules for when and how processes send & respond to messages
D. address to identify the ID of the sender
Local DNS name server has the following except: A. does not strictly belong to hierarchy B. each ISP (residential ISP, company, university) has one, also called "default name server" C. when host makes DNS query, query is sent to its local DNS server D. does not have local cache of recent name-to-address translation pairs E. acts as proxy, forwards query into hierarchy
D. does not have local cache of recent name-to-address translation pairs
TCP services include the following except: A. reliable transport between sending and receiving process B. flow control: sender won't overwhelm receiver C. congestion control: throttle sender when network overloaded D. provide timing, minimum throughput guarantee, security E. connection-oriented: setup required between client and server processes
D. provide timing, minimum throughput guarantee, security
When a UDP segment is lost (i.e., is not received at the destination), UDP re-sends it. True False
False
When layering is used, a protocol at one layer needs to understand how all other layers function. True False
False
POP3 has the following except: A. Download the email to your device from the email servers B. downloads what is in your inbox folder C. download draft, sent, delete, or others D. The email is deleted on the mail server once it is download to a device E. synchronizes emails between different devices. F. c& e
F. c& e C. download draft, sent, delete, or others E. synchronizes emails between different devices
1 bit contains 8 bytes. True False
False
A TCP header length is fixed of 20 Bytes True False
False
A full mesh topology of 6 nodes has 19 links. True False
False
A home network is a WAN. True False
False
A local area network (LAN) is a network that extends over a large geographical area. True False
False
All Web applications require 100% reliability.
False
All academic institutions in the world have Web sites ending with ".edu" True False
False
Because TCP is reliable, TCP segments never get lost. True False
False
Disadvantages of star topology are packet collisions and every station received all network traffic. A. True B. False
False
For a protocol to be reliable, it must be connection-oriented. True False
False
HTTP error 400 (Bad Request) means that the server did not find the page requested by the browser. True False
False
In TCP/IP, a transport-layer protocol uses the services of an application-layer protocol. True False
False
In client-server applications, the client does most of the work. True False
False
In iterative DNS name resolution, most of the burden falls on the root DNS servers. True False
False
In network extended star topology, each device is connected directly to all other devices and it is called a tree topology. A. True B. False
False
Multiplexing allows one message to contain data that belong to several applications. True False
False
PDF (Portable Document Format) is an open standard to present documents. True False
False
TCP is a proprietary standard. True False
False
The Internet is a LAN True False
False
The Internet is under the control of a single organization. True False
False
The Web browser Google Chrome can only communicate with Apache HTTP servers. True False
False
The bit ACK in not needed in the process of establishing a TCP connection. True False
False
The bit FIN is needed to establish TCP connections True False
False
The command RETR in FTP is used to retrieve the password needed to open a file. True False
False
The extended star topology does not suffer from the problem of single point of failure. True False
False
There are 13 authoritative DNS servers in the world. True False
False
There are 15 DNS root servers. True False
False
Typically, FTP servers listen on port 80. True False
False
UDP is an application layer protocol. True False
False
UDP is reliable. True False
False
UDP segments contain a field sequence_number to order segments at the destination. True False
False
WAN (Wide Area Network) is to Connects multiple devices for the use of a single user, Bluetooth is one example. A. True B. False
False
When FTP is used to transfer a file, data (i.e., bytes of the file) is transmitted on the control channel. True False
False
What makes browsing the Internet reliable is not the fact that HTTP is inherently reliable but the fact that HTTP (which is unreliable) uses TCP which is reliable. True False
True
What follows is a fill in the blank question with 1 blanks. as an example of Transport protocol that is connection orient is
TCP
When TCP receives a message from an application layer protocol (such as HTTP), it adds a TCP header to that message and the result is a TCP segment. True False
True
A Personal Area Network (PAN) connects multiple devices for the use of a single user. True False
True
A Web server is a computer that runs a program called an HTTP server such as Apache HTTP server. True False
True
A benefit of the star topology is that if one cable or host fails, the rest of the network continues to function properly. True False
True
A browser uses a network to connect to a Web server. True False
True
A computer network is a set of connected devices (servers, PCs, laptops, phones, routers, switches, etc.) that exchange data with each other. A. True B. False
True
A connection-oriented protocol requires a phase where two parties establish a connection before they start communicating (i.e., exchanging information). True False
True
A problem with the Ring topology is that one cannot add or remove hosts without shutting down the entire network. A. True B. False
True
A protocol is a "shared language" that two entities use to communicate over a network. True False
True
A reliable protocol is a protocol that guarantees that any information sent will be properly received. True False
True
A socket is an IP address and a port number. True False
True
A standard is an accepted model of building or way of doing something. True False
True
A wide area network (WAN) is a network that extends over a large geographical area. True False
True
An application layer protocol defines the rules for when and how messages must be sent, e.g., when the server receives a request of type A, it must reply with a response of type B. True False
True
Browsing the Web is a network application. True False
True
Currently, most networks are packet switched and it is called IP networking. A. True B. False
True
DNS can be thought of as the phonebook of the Internet. It translates names into IP addresses. True False
True
Flow control in TCP uses the field receive_window in the TCP header. True False
True
HTTP is an example of an application layer protocol. True False
True
In TCP/IP, providing a reliable communication means making sure that what a sender sends is properly received by the receiver. True False
True
In TCP/IP, the network layer is responsible for routing messages across networks. True False
True
In a P2P application, a peer may at times be requesting a service from other peers and it may at times be providing a service to other peers. True False
True
In a client-server application, an application layer protocol defines the types of messages exchanged between the clients and the server, e.g., request, response. True False
True
In a ring topology, one workstation malfunction takes out the entire network. True False
True
In client-server applications, the server is considered a single point of failure. True False
True
In peer-to-peer (P2P) applications, all machines are equal. True False
True
Layered communication makes troubleshooting easier. True False
True
Local DNS servers may use a local cache to avoid repeating the name resolution process for IP addresses already retrieved. True False
True
Networks are needed to send emails. True False
True
Routers are devices that provide services at all three layers: network layer, link layer, and physical layer. True False
True
The DNS name resolution process finds the IP address of given host name. True False
True
The Internet is a network of networks. True False
True
The Internet is the largest WAN in existence. True False
True
A Campus Area Network (CAN) is a network that may span multiple buildings. True False
true
DNS stores the mappings between human-readable names of hosts on the Internet and their IP addresses. True False
true