CCNA 2/M8: TCP/IP Error and Control Messages
Online Curriculum Notes
Curriculu
m
overview
Question
Answer
1.
What deliver method does IP use?
Best effort
2.
What are three reasons data may fail to
reach its destination?
Hardware failure
Improper configuration
Incorrect routing info
3.
What does IP use to notify the sender
that the message couldn't be delivered?
What type of message provides
information or configuration parameters
to hosts?
What component of TCP/IP notifies the
sender that a data transmission has
failed?
What is the acronym for Internet Control
Message Protocol?
Does a router know the exact path a
datagram took to get to the router?
ICMP
What is the ONLY information a router
has about a datagram?
only the source and destination
Does ICMP correct network problems?
no
10. Does ICMP notify the intended receiver
that there was a problem delivering the
packet?
11. Why don't errors created by ICMP
messages generate their own ICMP
message?
no
4.
8.1.1
5.
6.
8.1.2
7.
8.
9.
8.1.3
Control messages
ICMP
ICMP
no
IP addresses of the datagram.
error reports could generate more
error reports, causing increased
congestion on an already ailing
network
8.1.4
12. What 3 addresses are needed in the
TCP/IP configuration if datagrams are to
travel outside the local network?
IP
SNM
Default Gateway
13. What two things must a router have in
order to send datagrams?
TCP/IP properly configured on it's
interfaces
Appropriate routing protocol
8.1.5
14. What is the term that is used when a
destination network is not accessible?
15. What happens if the destination device
receives the ICMP echo request?
16. What command is initiates an echo
request?
Unreachable network
it formulates an echo reply
message to send back to the
source of the echo request
ping
1
8.1.6
8.1.7
8.1.8
17. If a request is successful between the
source and destination, what does it
mean?
18. What would be created if two routers
continually route a datgram back and
forth?
19. What is the maximum hop count for
RIP?
20. What is TTL?
21. What three fields are common to all
ICMP messages?
22. What are four reasons datagrams may
not make it to their destination?
23. If a "3" appears in the type field, what
does that mean?
24. What does the "code value" indicate?
8.1.9
8.2.1
8.2.2
8.2.3
25. What is usually needed to forward a
datagram from a token-ring to an
Ethernet network?
26. If a datagram header has an error, what
will a device like a router do?
27. When the code value of the problem
message reaches 0, what will the
pointer field indicate?
28. Why is a control message sent?
29. How are ICMP control messages sent?
30. What's another term for "gateway"?
31. What is the only device that can initiate
a Redirect/Change request message?
32. How is a redirect/change configured on
a Cisco router?
33. What allows a host to ask for the current
time according to the remote host?
34. What are the 2 type fields on an ICMP
timestamp message?
35. What 3 things are contained in the ICMP
timestamp reply message?
36. What 2 things affects true transit time?
8.2.4
37. What 2 protocols are now used to allow
a host to find it's network number?
confirming IP connectivity
between the two devices
Loop - travels in circles
15
Time to live
Type
Code
Checksum
Hardware failures
improper protocol configuration
down interfaces
incorrect routing information
Destination unreachable
The reason the packet could not
be delivered
Packet fragmentation
It sends an ICMP type 12
parameter problem message to
the source
the octet of the datagram that
produced the error
To inform hosts of conditions
such as network congestion or a
better gateway
Inside IP dtagrams
router
router
It's the default
The ICMP timestamp request
message
13 (timestamp request) or
14 (timestamp reply). The code
field value is always set to 0
because there are no additional
parameters available
the originate, receive and
transmit timestamps
Traffic and congestion on the
network
BOOTP
DHCP
2
8.2.5
8.2.6
8.2.7
8.2.8
38. What type of message is sent out when
a host doesn't know the network
address?
39. What is the multicast address for router
discovery?
Address mask request
40. What happens if a router receives the
multicast but isn't configured for
multicasting?
41. If the default gateway is missing, what is
the message generated by the host?
42. What happens when there is too much
congestion on a network?
43. Why don't Cisco routers send sourcequench messages (by default)?
It doesn't answer the request
44. What type of office might use sourcequench messages?
small office home office
(SOHO)
224.0.0.2
router solicitation
Packets are dropped
because the source-quench
message may itself add to the
network congestion.
3