CCNA 2/Mod 7: Distance Vector Routing – Online Curriculum Study Guide
Curriculum
7.1.1
7.1.2
7.1.3
7.1.4
7.1.5
7.1.6
Question
1. What are the two ways that routing
table updates occur in a distance
vector protocol?
2. What does a router send to its
adjacent routers when it updates?
3. What occurs when inconsistent
routing tables are not updated due to
slow convergence in a changing
network?
4. What is the term when all routers have
consistent knowledge or the NW and
correct routing tables?
5. What is the term loops packets
continuously around the network even
when the destination network is down?
6. Why do packets loop through the
network ?
7. If a hop count metric is set to 15, what
will happen when the packet hops to
16?
8. What is the term for a situation when
incorrect information has been sent
back to the router that originally sent
the information and it’s not accurate?
9. What two things are reduced by split
horizon?
10. What type of protocols use route
poisoning?
11. How can large routing loops be
avoided?
12. Do routers have to wait 30 seconds
before advertising poisoned routes?
13. ROUTERF is running RIP. ROUTERE
detects that ROUTERF is down. It
advertises the NW for this link with a
hop count metric of 16. What routing
loop prevention method is en effect?
14. How often does RIP send updated
routing tables?
15. When is a triggered update sent?
16. What causes a triggered update?
17. Who sends a triggered update?
Answer
1. periodically
2. topology change in NW
Its entire routing table
Routing loops
network is said to have converged
count to infinity
because of wrong information in the
routing tables
It’s discarded
Split horizon
1. reduces incorrect routing
information
2. reduces routing overhead
Distance vector
setting the hop count to one more than the
maximum
no
Route poisoning
30 seconds
Immediately
Change in topology
The router that detected the topology
change
1
7.1.7
7.2.1
7.2.2
7.2.3
7.2.4
18. When does a distance vector routing
protocol set a hold-down timer on a
route?
19. What does a router do when it
receives an update from a neighbor
router with a better metric than it had
originally recorded?
20. Why is an update with a poorer metric
ignored?
21. Which version of RIP is classless?
22. Which version of RIP supports VLSM?
23. What is the maximum number of hops
in a path?
24. What happens when the hop count is
incremented +1 every hop and
reaches 16?
25. What two commands are required to
enable RIP on an interface?
26. What mode must you be in to set
these two commands?
27. What will happen to packets when the
no ip classless command is disabled?
28. What will happen to packets when the
no ip classless command is disabled
AND there is a default route defined?
29. What is the term to indicate that all the
routers in the internetwork have the
same routing information?
30. What causes routing loops and
counting to infinity in RIP routers?
31. What do holddown timers do to
convergence?
32. What is the default holddown time for
RIP?
33. What would you do to decrease the
network’s convergence time?
34. If you have 4 routers and updates are
send every 50 seconds, what would
the longest loop be?
35. What is RIP’s update interval default
time?
36. What will this command do to a
router?
When it’s marked as inaccessible
The router marks the NW as accessible
and removes the holddown timer
It allows more time for the knowledge of a
disruptive change to propagate through
the entire NW
V2
V2
15
it is considered to be infinity and the
network
Router RIP command
Networks (attached)
Global
Any packets received that are destined for
a subnet that numerically falls within the
router’s SN addressing scheme will be
discarded
Packets discarded
Convergence
Inconsistencies due to routing update
messages with out of date routes being
propagated around the internetwork
Increase it
180 seconds
Change it LOWER than 180
4 x 50 = 200 seconds
30 seconds
Decrease convergence time
GAD(config-router)#update-timer
15
2
37. What will this command do?
GAD(config-interface)#ip rip
send version 2
7.2.5
38. How are RIP routes indicated when
you key the show ip route
Configures an interface to send version 2
packets
With an “R”
command?
39. The following line was shown in the
output of the show ip route
command. What is the administrative
distance of the routing protocol?
120 or RIP
192.168.3.0/24 (120/1) via
192.168.2.2, 00:00:30,
Serial 0/0
7.2.6
7.2.7
7.2.8
7.2.9
40. What are the three most common RIP
configuration errors?
41. What command verifies that routing
updates are being sent and received?
42. What affect do route filters have on
link state protocols?
43. When you use the passive interface
command, you prevent routers from
sending routing updates through an
interface. What type of routes are you
preventing other systems on the
network from learning?
44. What is the maximum paths RIP can
load balance over?
45. What is the term used when routers
“take turn” load balancing?
46. If using RIP, which path will be given
preference – a 56Kbps or a 155
Mbps?
1. an incorrect network statement
2. discontiguous subnets
3. split horizon
Debug ip rip
None
dynamic
6
Round robin
Neither --- RIP’s metric is hop – not
speed
47. When a router learns multiple routes to a
specific network which route is installed in
the routing table?
, the route with the lowest administrative
distance
48. How many default static routes are
installed when load balancing?
49. What are the 2 methods of load
balancing Cisco IOS offers?
50. What is IGRP’s default administrative
distance?
51. What is RIP’s default administrative
distance?
52. Why would a static route be chosen
over a RIP route?
6
1. per packet
2. per destination
100
120
Lower AD
Static = 1 RIP = 120
3
7.2.10
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
7.3.6
7.3.7
7.3.8
53. How would an administrator configure
a static route for use if a primary route
failed?
Configure the route with a metric greater
54. When an interface goes down, what
happens to all static routes pointing
out that interface?
They are removed from the IP routing
than the default value
table.
55. What 2 functions do routers perform
as routing information spreads
throughout the network?
1. learn of failures
56. How often does IGRP send updates?
90 seconds
57. What are IGRP’s two default metrics?
Bandwidth
Delay
MTU
58. What is the acronym for Maximum
Transmission Unit?
59. Which routes within an AS do NOT
include subnet information?
60. What routes support numbering
outside the private network without
renumbering inside?
61. What is used to prevent regular
updates from inappropriately
reinstating a route that may not be up?
62. What is used to prevent large routing
loops?
63. If IGRP updates every 90 seconds, by
default, how long will a router wait
before declaring a route invalid?
(invalid timer)
64. How long would this same route be in
holddown?
65. What is the command to configure
IGRP?
No questions – it’s your lucky day!
66. What command is used to verify that
IGRP has been configured properly?
67. How are IGRP routes displayed on the
output?
68. What are the 3 most common IGRP
configuration errors?
2. ID new destinations
System
Interior routes
Holddowns
Poison reverse updates
3x update period or
3 x 90 = 270
280 sec
ROUTER(config)#
show ip route
I
1. mistyped network
statement
2. discontiguous subnets
3. incorrect AS
4