MidTerm Comp Net Review
Layering provides modularity, which makes it much easier to change implementation of services provided at each layer, and keep the remainder of the system unchanged if a layer's implementation is changed(T/F)
True
The buffer size used in the socket recv() method at the server side program should be equal to the length of the data provided to the socket send() method at the client side program(T/F)
True
The following statement is completely correct: By default, HTTP runs on port 80 and HTTPS runs on port 443
True
The port numbers used in the socket server program and client program MUST be the same(T/F)
True
The return value of the socket method accept() is a pair (conn, address), where conn is a new socket object that can be used to send and receive data on the connection(T/F)
True
Web servers can use caching and multiple threading to improve performance(T/F)
True
Wireshark is a packet sniffer that can be used to capture and analyze network packets.(T/F)
True
With client-server socket programming, the server program uses two sockets: one socket is used to listen for incoming connection requests, the other one performs data transfer with a client program(T/F)
True
How an application at layer 5 uses the services at layer 4 in the TCP/IP model? through a network address which is an IP address through a network address which is a port number through a transport address which is an IP address through a transport address which is a port number
through a transport address which is a port number
Which of the following is the correct display filter that shows all TCP traffic running on port 80 on Wireshark? tcp and tcp.port == 80 tcp == 80 tcp.port = 80 tcp or tcp.port == 80
tcp and tcp.port == 80
The arp -a command displays IP configuration of your computer Interface configuration of your computer Network connections with other hosts the current contents of the ARP cache table on your computer
the current contents of the ARP cache table on your computer
# the Python statement below opens the file to writef = open(file, 'wb') The option 'b' means write data to the file one byte at a time the file will be opened for both write and read the file will be opened in text mode the file will be opened in binary mode
the file will be opened in binary mode
Which of the following is NOT defined in a network protocol? the format of messages sent and received among networking hosts the length of messages sent and received among networking hosts the actions taken on message transmission and receipt or other events the order of messages sent and received among networking hosts
the length of messages sent and received among networking hosts
The backlog argument provided for the listen() method specifies the server will listen for incoming requests for 5 minutes the minimum number of queued connections the server will listen for incoming requests for 5 seconds the maximum number of queued connections
the maximum number of queued connections
Which of the following is NOT a reason why the OSI model is preferred to use when we study network security issues? The Application layer is further divided into three independent sub-layers, which makes it much easier to change implementation of service provided at each sub-layer The Application layer is further divided into three independent sub-layers, which keeps the remainder of the networking system unchanged if the implementation of one sub-layer is modified the more layers the better in any protocol models If the TCP/IP model is used in such cases, there will be too many protocols in the Application layer and it makes the studying/analysis at this layer inefficient
the more layers the better in any protocol models
Many business computers have three distinct and worldwide unique identifiers. Which of the following does NOT belong to these unique identifiers? the IP address the DNS name the port number the Ethernet address
the port number
What technology allows an HTTP client to retrieve individual data items from Web server to update a section of the webpage without having to reload an entire page? JSON AJAX HTML XML
AJAX
What protocol is used to determine the Layer 2 MAC address of a host when its Layer 3 IP address is known? IP ARP ICMP TCP
ARP
For an application with a server and several remote clients calling transport service primitives, a client first executes a CONNECT primitive, and then the server executes a LISTEN primitive(T/F)
False
If a socket is created with the socket type SOCK_STREAM, then it is a UDP socket which is connectionless(T/F)
False
In packet-switched networks, the resources needed along a path to provide for communication between the end systems are reserved for the duration of the communication session(T/F)
False
TCP uses the fast-start procedure to increase the throughput rapidly to improve the performance of data communication between two application end points(T/F)
False
Which of the following Wireshark features is to recover a file for captured FTP data packets? Convert Recover Copy Follow Stream
Follow Stream
The following are the HTTP Request Methods in HTTP 1.0 EXCEPT FOR PUT POST GET HEAD
PUT
Which of the following app-layer protocols ONLY uses TCP services at Layer 4? SNMP DHCP DNS HTTPS
HTTPS
What is the minimum size of a TCP segment? 20 bytes 24 bytes 32 bytes 16 bytes
20 bytes
How many columns in the DNS database table? 5 3 4 6
5
What is the minimum size of a UDP segment? 4 bytes 32 bytes 16 bytes 8 bytes
8 bytes
"HTTP 1.1 supports pipeline requests" means A client browser can send the 2nd request to a Web server before the response to the 1st request has arrived A Web server can send all the requested resources within one response page A client browser has to hold for sending the 2nd request to a Web server before the response to the 1st request has arrived A Web server can send the 2nd request to a client browser before the response to the 1st request has arrived
A client browser can send the 2nd request to a Web server before the response to the 1st request has arrived
Which of the following application-layer protocols is on top of UDP? SNMP FTP HTTP HTTPS
SNMP
In packet-switching networks, the computing devices are interconnected through communication links and packet switches(T/F)
True
What command restarts the DHCP lease process in Windows? ipconfig /all ifconfig /renew ipconfig /renew ifconfig -a
ipconfig /renew
Which of the following is a new HTML 5 feature that are NOT available in HTML 4? native audio and video support hyperlinks image support HTML forms
native audio and video support
Which of the following Wireshark display filters gets all HTTP and FTP traffic with 192.168.1.33 being either the source IP or the destination IP? (http or ftp) and ip.src == 192.168.1.33 (http and ftp) and ip.dst == 192.168.1.33 (http and ftp) and ip.addr == 192.168.1.33 (http or ftp) and ip.addr == 192.168.1.33
(http or ftp) and ip.addr == 192.168.1.33
Name the four steps, in order, in a successful DHCP process -Receive DHCP server offer -DHCP server discovery -DHCP request from server offers -Server DHCP acknowledgement for request confirming parameters -DHCP request from server offers -DHCP server discovery-Receive DHCP server offer-Server DHCP acknowledgement for request confirming parameters -DHCP server discovery-Receive DHCP server offer-DHCP request from server offers-Server DHCP acknowledgement for request confirming parameters -Receive DHCP server offer -DHCP request from server offers -DHCP server discovery-Server DHCP acknowledgement for request confirming parameters
-DHCP server discovery-Receive DHCP server offer-DHCP request from server offers-Server DHCP acknowledgement for request confirming parameters
What is the size of an IP pseudo-header for IPv4? 20 bytes 12 bytes 8 bytes 16 bytes
12 bytes
Which of the following statements is TRUE about HTTP request messages?
Accepts header gives the browser a chance to tell the Web server which format it wants for a resource
What is another name for a CNAME record? IP address Alias Host Port number
Alias
Which of the following statements is TRUE? Both ends of a TCP connection can always release the connection if the server can receive at least one DR (Disconnect Request) sent from the client, with the help of timers and retransmission Both ends of a TCP connection can always release the connection even if all the DRs (Disconnect Requests) are lost, with the help of timers and retransmission A DR (Disconnect Request) should be initiated by the server host Both ends of a TCP connection can always release the connection even if every DR (Disconnect Request) sent from the client is lost, with the help of timers and retransmission
Both ends of a TCP connection can always release the connection if the server can receive at least one DR (Disconnect Request) sent from the client, with the help of timers and retransmission
Which of the following transport service primitives is ONLY called at the client side? SEND RECEIVE CONNECT DISCONNECT
CONNECT
Which of the following flags in the TCP header is used for congestion control? SYN CWR URG RST
CWR
The data unit at the network layer is segment IP datagram raw bits frame
IP datagram
What does an A record hold? IPv6 address Port number Hostname IPv4 address
IPv4 address
Which of the following application-layer protocols always uses UDP services at the transport layer? DHCP FTP DNS SSH
DHCP
Which of the following is TRUE about DNS? DNS uses ONLY UDP services at the trans-layer. DNS mostly runs on TCP Port 53 by default from the start. DNS uses ONLY TCP services at the trans-layer. DNS uses both TCP and UDP services at the trans-layer.
DNS uses both TCP and UDP services at the trans-layer.
Which of the following app-layer protocols runs on top of TCP? DHCP SNMP POP-3 RTP
POP-3
Which of the following flags is TRUE if a TCP segment carries some data? PSH SYN FIN ACK
PSH
A client browser's state is maintained by using a database on the Web server a file on the Web server Cookies of a browser a file on the client machine
Cookies of a browser
The following networks are the same as Wi-Fi except for? Wireless Local Area Networks Ethernet LANs IEEE 802.11 networks Wireless LANs
Ethernet LANs
# A client program with socket programming has the following Python code: client_s.connect( (host, port ) ) # client_s represents the socket created by the client program In the above Python statement, host should hold the IP address of the client host (T/F)
False
DNS namespace is hierarchical from the root down with the root is named COM(T/F)
False
Which of the following app-layer protocol uses the standard port 443 by default? SSH FTP HTTPS HTTP
HTTPS
What is the TCP/IP protocol model designed for? It is designed to model the data communication between two Email applications It is designed to model the data communication between two hosts located within the same LAN It is designed to model the data communication between a client browser and a Web server It is designed to model the data communication between two applications running in two different hosts.
It is designed to model the data communication between two applications running in two different hosts.
Which of the following transport service primitives is ONLY called at the server side? LISTEN DISCONNECT SEND RECEIVE
LISTEN
Which of the following is NOT true about the layered architecture used in computer networking? When a layer's implementation is changed, the remainder of the system remains unchanged It allows us to discuss and better understand a well-defined, specific part of a large and complex system Layer architecture is ONLY used in the TCP/IP model, NOT in the OSI model It provides modularity and makes it much easier to change implementation of service provided at each layer
Layer architecture is ONLY used in the TCP/IP model, NOT in the OSI model
HTML content type is identified by an HTML engine an HTML interpreter an HTML parser MIME
MIME
Which of the following is NOT a network application? Web severs/browsers text messaging systems Microsoft PowerPoint application e-mail systems
Microsoft PowerPoint application
The following are reasons why DNS is needed EXCEPT FOR Servers' IP addresses are permanent and never change High-level, readable names are needed in order to decouple computer names from IP addresses Computers ONLY understand numerical IP addresses, some mechanism is required to convert the names to IP addresses Programs could refer to Web pages and other resources by using IP addresses of the servers, but these IP addresses are hard to remember
Servers' IP addresses are permanent and never change
__________ allows the sender to send multiple frames before needing the acknowledgements Buffering at both ends Buffering at the receiver Buffering at the sender Sliding window
Sliding window
In Python, to write to an existing file, you must add a parameter to the open() function: "a" - Append - will append to the end of the file "w" - Write - will overwrite any existing content (T/F)
True
You can use the Wireshark feature under which of the following menu items to recover a file for captured FTP data packets? View -> conversations Analyze -> conversations Statistics -> convert Statistics -> conversations
Statistics -> conversations
Comparing TCP with UDP, which of the following is NOT true? UDP has less protocol overheads TCP is more efficient TCP has more protocol overheads UDP is more efficient
TCP is more efficient
Which of the following is an interface of data communication between the Transport layer (layer 4) and the App layer (layer 5)? DSAP ASAP TSAP NSAP
TSAP
Which of the following is NOT a correct statement for the Internet? The Internet is a computer network that interconnects billions of computing devices via coaxial cable, copper wire, or optical fiber The Internet can be described as a networking infrastructure that provides services to network applications The Internet is a computer network that interconnects billions of computing devices throughout the world The Internet is a computer network of networks
The Internet is a computer network that interconnects billions of computing devices via coaxial cable, copper wire, or optical fiber
A TCP segment with the flags SYN = 1 and ACK = 0 This type of segment can be bidirectionally, either from a client host to a server, or from a server host to a client This is a connection acceptance segment sent from a server host This is a connection request segment sent from a client host This segment can be sent from a server host
This is a connection request segment sent from a client host
Why would an ARP frame have a destination MAC address of 00:00:00:00:00:00? To indicate the ARP frame was broadcasted to ONLY one host on the network. To indicate the ARP frame was broadcasted to all the hosts on the network. To indicate the ARP frame was broadcasted to NONE of the hosts on the network. A destination MAC address of 00:00:00:00:00:00 does not exist.
To indicate the ARP frame was broadcasted to all the hosts on the network.
A DNS server uses well-known UDP port 53 for all its UDP activities(T/F)
True
A DNS zone is a portion of the DNS namespace that is managed by a specific organization or administrator(T/F)
True
A browser plug-in extends the browser for supporting new file types(T/F)
True
A packet is stored at a router until it has fully arrived (T/F)
True
After a socket is created, it should be bound to a local address (HOST, PORT) before it can listen to incoming connection requests(T/F)
True
After the listen() method is called by the server program, it is ready to accept connection requests(T/F)
True
The methods that are used to improve the performance of Web applications include the following EXCEPT FOR Multiple-threading Using a different browser Server-side caching Client-side caching
Using a different browser
What is the solution to browsers' problem of supporting a rapidly growing collection of file types? When a server returns a page, it also returns some additional information about the page including its MIME type A Web server maintains a table of MIME type Update a browser by adding more functions Update a browser by adding more modules
When a server returns a page, it also returns some additional information about the page including its MIME type
To clear the arp cache, use the following command arp -c arp -clear arp -d arp -a
arp -d
Which of the following TCP header fields is used for TCP flow control ? Checksum Urgent pointer Window size the ECE flag bit
Window size
A TCP segment with the flags SYN = 1 and ACK = 1 can be used as connection request segment can ONLY be sent from a server host to a client host can be sent from either direction between a client and a server can ONLY be sent from a client host to a server host
can ONLY be sent from a server host to a client host
Which of the following statements is NOT true about TCP? it provides flow control delivery of messages to their destinations are not guaranteed it provides congestion control it provide connection-oriented services
delivery of messages to their destinations are not guaranteed
The data unit at the data link layer is segment frame packet raw bits
frame
Which of the following is the correct display filter that shows all Web traffic on Wireshark? http http and https http or https https
http or https
What command can be used to display the IP address, subnet mask and default gateway in Linux? ip ip_addr ipconfig ifconfig
ifconfig
What command can be used to display the IP address, subnet mask and default gateway in Windows? ifconfig ipconfig ifconfig -a ip
ipconfig
What command with which switch can be used to display the IP address, subnet mask, default gateway, DNS server, and DHCP server in Windows? ipconfig /all ifconfig -a ipconfig -a ifconfig -all
ipconfig /all
What command clears the DNS cache on a Windows machine? ipconfig /flush ifconfig /flush ifconfig /flushdns ipconfig /flushdns
ipconfig /flushdns
To request a new IP address from a DHCP server, run the following command ipconfig /renew ipconfig /request ipconfig /release ipconfig /all
ipconfig /renew
What command is used to display connection information of a host in Windows and Linux? netstat conninfo ifconfig ipconfig
netstat
Which of the following Wireshark display filters shows all the traffic except ARP, DNS and DHCP? not (arp or dns or dhcp) arp or dns or dhcp not (arp and dns and dhcp) arp and dns and dhcp
not (arp or dns or dhcp)
Which of the following is the correct display filter that shows everything but excludes FTP traffic on Wireshark? no ftp packets not ftp without ftp exclude ftp
not ftp
What command is used to lookup DNS information in both Windows and Linux? dnslookup ifconfig nslookup ipconfig
nslookup
What command is used to lookup DNS information in both Windows and Linux? nslookup dnslookup ifconfig ipconfig
nslookup
Which of the following terms has the meaning of this statement: taking a packet arriving on one of a host's incoming links and forwards it to one of the host's outgoing links according to its destination packets protocols network applications packet switches
packet switches
Which layer in the OSI model allows the two communicating applications to interpret the meaning of data exchanged? network layer presentation layer application layer session layer
presentation layer
The data unit at the physical layer is packets segments frames raw bits
raw bits
If a browser received a new file format from a Web server within an HTTP response page, it may not know how to interpret and display on it. The browser may send a message to the Web server refer to a table of MIME types look at the cookies stored in the browser ask the Web server how to interpret it
refer to a table of MIME types
The data unit at the transport layer is packet frame raw bits segment
segment
Which of the following is NOT a URL protocol? http ftp snmp https
snmp
