M6: Verifying Connectivity

Question 1

What are the functionalities built into protocols and devices that protect against issues?

Answer 1

Error detection and error recovery

Question 2

What is the Ability for a protocol or program to determine that something went wrong

Answer 2

error detection

Question 3

the ability for a protocol or program to attempt to fix something that went wrong

Answer 3

error recovery

Question 4

What are used buy multiple layers to make sure that the correct data was received by the receiving end?

Answer 4

cyclical redundancy checks

Question 5

What happens if a CRC value doesn’t match the data payload?

Answer 5

the data is discarded

Question 6

What layer decides if data needs to be resent?

Answer 6

the transport layer

Question 7

When network problems come up what is the most common issue I’ll run into?

Answer 7

inability to establish a connection

Question 8

what protocol is used to communicate issues of network errors, a router not knowing how to route a destination, a certain point not being reachable, the time to live of an IP data gram expired and no further hops will be attempted, etc?

Answer 8

ICMP, internet control message protocol

Question 9

what protocol is mainly used by a router or remote host to communicate why transmission has failed back to the origin of the transmission?

Answer 9

ICMP

Question 10

describe the makeup of an ICMP packet

Answer 10

Header with a few fields, data section used by a host to figure out which of their transmissions generated the error.

Question 11

Which field in an ICMP packet is the first field, 8 bits long, and specifies what type of message is being delivered?

Answer 11

Type field

Question 12

what field of an ICMP packet would you find the destination unreachable or time exceeded information, as the type of message?

Answer 12

Type field

Question 13

what is the second field in the ICMP Packet, * bits, which indicates a more specific reason for the message than just the type?

Answer 13

Code field

Question 14

what are individual codes or examples of them for the destination unreachable type of ICMP packet/

Answer 14

destination network unreachable, destination port unreachable

Question 15

What ICMP packet field, the third field, is a 16 bit field that a CRC is performed on later/

Answer 15

Check sum field

Question 15

What is the fourth ICMP header field, a thirty two bit field optionally used by some of the specific types and codes to send more data?

Answer 15

Rest of header

Question 15

In ICMP, what exists so that the recipient of the message knows which of their transmissions cause the error being reported? containing the entire IP header and the first 8 bytes of the data payload section of the offending packet.

Answer 15

Payload of the ICMP packet

Question 16

Was ICMP designed for humans to interact with it?

Answer 16

no

Question 17

What is the point of ICMP packets?

Answer 17

So that error messages can be delivered between network computers automatically

Question 18

What tool for ICMP is useful to human operators?

Answer 18

Ping

Question 19

What tool exists on every operating system and has for a long time?

Answer 19

Ping

Question 20

What tool lets you send a special type of ICMP message called an Echo request?

Answer 20

PIng

Question 21

What kind of message asks a destination if it is there?

Answer 21

ICMP echo request

Question 22

In Pinging, what kind of message will be sent back if the destination is up and running and able to communicate on the network?

Answer 22

ICMP Echo Reply Message type

Question 23

How can I invoke the ping command?

Answer 23

command line, type ping and a destination IP or fully qualified domain name.

Question 24

When pinging, what displays the address sending the ICMP echo reply and how long it took for the round-trip communications?

Answer 24

Every line of output

Question 25

What does every line of output have on top of the address sending the ICMP echo reply and how long it tooK?

Answer 25

the TTL remaining and how large the ICMP message is in bytes

Question 26

What happens when the ping command ends? What is displayed?

Answer 26

statistics like Percentage of packets transmit then received, average round trip time.

Question 27

where will the pink command run until it is interrupted by an end user sending an interrupt event?

Answer 27

Linux and MacOS

Question 28

how does an end user send an interrupt event?

Answer 28

Press Ctrl+C

Question 29

Where does pinging default to only sending four echo request?

Answer 29

windows OS

Question 30

what does ping’s support that lets you change its behavior, like the number of echo request to send, how large they should be, and how quickly they should be sent?

Answer 30

command line flags