Unit 5-10 Exam II Flashcards
- Which statement describes a feature of the IP protocol?
IP relies on Layer 2 protocols for transmission error control.
MAC addresses are used during the IP packet encapsulation.
IP relies on upper layer services to handle situations of missing or out-of-order packets.
IP encapsulation is modified based on network media.
IP relies on upper layer services to handle situations of missing or out-of-order packets.
Explanation: IP protocol is a connection-less protocol, considered unreliable in terms of end-to-end delivery. It does not provide error control in the cases where receiving packets are out-of-order or in cases of missing packets. It relies on upper layer services, such as TCP, to resolve these issues.
What is message encoding?
message encoding : the process of converting information from one format into another acceptable for transmission
What is message sizing?
message sizing : the process of breaking up a long message into individual pieces before being sent over the network
- Which method would an IPv6-enabled host using SLAAC employ to learn the address of the default gateway?
router advertisement messages received from the link router
router solicitation messages received from the link router
neighbor advertisement messages received from link neighbors
neighbor solicitation messages sent to link neighbors
router advertisement messages received from the link router
42. A user issues a ping 192.168.250.103 command and receives a response that includes a code of 1. What does this code represent? network unreachable port unreachable protocol unreachable host unreachable
host unreachable
- What are three responsibilities of the transport layer? (Choose three.)
identifying the applications and services on the client and server that should handle transmitted data
conducting error detection of the contents in frames
meeting the reliability requirements of applications, if any
directing packets towards the destination network
formatting data into a compatible form for receipt by the destination devices
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
meeting the reliability requirements of applications, if any
multiplexing multiple communication streams from many users or applications on the same network
Explanation: The transport layer has several responsibilities. Some of 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
Multiplexing the communications of multiple users or applications over a single network
Managing the reliability requirements of applications
- How does network scanning help assess operations security?
It can detect open TCP ports on network systems.
It can detect weak or blank passwords.
It can simulate attacks from malicious sources.
It can log abnormal activity.
It can detect open TCP ports on network systems.
Explanation: Network scanning can help a network administrator strengthen the security of the network and systems by identifying open TCP and UDP ports that could be targets of an attack.
- Which two operations are provided by TCP but not by UDP? (Choose two.)
retransmitting any unacknowledged data
acknowledging received data
reconstructing data in the order received
identifying the applications
tracking individual conversations
retransmitting any unacknowledged data
acknowledging received data
Explanation: Numbering and tracking data segments, acknowledging received data, and retransmitting any unacknowledged data are reliability operations to ensure that all of the data arrives at the destination. UDP does not provide reliability. Both TCP and UDP identify the applications and track individual conversations. UDP does not number data segments and reconstructs data in the order that it is received.
- A user is executing a tracert to a remote device. At what point would a router, which is in the path to the destination device, stop forwarding the packet?
when the router receives an ICMP Time Exceeded message
when the RTT value reaches zero
when the values of both the Echo Request and Echo Reply messages reach zero
when the host responds with an ICMP Echo Reply message
when the value in the TTL field reaches zero
Explanation: When a router receives a traceroute packet, the value in the TTL field is decremented by 1. When the value in the field reaches zero, the receiving router will not forward the packet, and will send an ICMP Time Exceeded message back to the source.
- A network administrator is testing network connectivity by issuing the ping command on a router. Which symbol will be displayed to indicate that a time expired during the wait for an ICMP echo reply message?
U
.
!
$
.
Explanation: When the ping command is issued on a router, the most common indicators are as follows:
! – indicates receipt of an ICMP echo reply message
. – indicates a time expired while waiting for an ICMP echo reply message
U – an ICMP message of unreachability was received
- A technician is configuring email on a mobile device. The user wants to be able to keep the original email on the server, organize it into folders, and synchronize the folders between the mobile device and the server. Which email protocol should the technician use?
SMTP
MIME
POP3
IMAP
IMAP
- At which OSI layer is a source MAC address added to a PDU during the encapsulation process?
application layer
presentation layer
data link layer
transport layer
data link layer
- Which value, that is contained in an IPv4 header field, is decremented by each router that receives a packet?
Time-to-Live
Fragment Offset
Header Length
Differentiated Services
Time-to-Live
Explanation: When a router receives a packet, the router will decrement the Time-to-Live (TTL) field by one. When the field reaches zero, the receiving router will discard the packet and will send an ICMP Time Exceeded message to the sender.
- Which two ICMP messages are used by both IPv4 and IPv6 protocols? (Choose two.)
route redirection neighbor solicitation router solicitation router advertisement protocol unreachable
route redirection
protocol unreachable
Explanation: The ICMP messages common to both ICMPv4 and ICMPv6 include: host confirmation, destination (net, host, protocol, port) or service unreachable, time exceeded, and route redirection. Router solicitation, neighbor solicitation, and router advertisement are new protocols implemented in ICMPv6.
- What mechanism is used by a router to prevent a received IPv4 packet from traveling endlessly on a network?
It checks the value of the TTL field and if it is 100, it discards the packet and sends a Destination Unreachable message to the source host.
It decrements the value of the TTL field by 1 and if the result is 0, it discards the packet and sends a Time Exceeded message to the source host.
It checks the value of the TTL field and if it is 0, it discards the packet and sends a Destination Unreachable message to the source host.
It increments the value of the TTL field by 1 and if the result is 100, it discards the packet and sends a Parameter Problem message to the source host.
It decrements the value of the TTL field by 1 and if the result is 0, it discards the packet and sends a Time Exceeded message to the source host.