NTP

Question 1

What is the purpose of NTP

Answer 1

Synchronizing internal clocks across all devices on a network

Question 2

What is the command to view the time in Cisco IOS

Answer 2

sh clock

Question 3

What is the default timezone for Cisco devices

Answer 3

UTC

Question 4

What is the command to view the time source on Cisco devices

Answer 4

sh clock detail

Question 5

What is the default time source for Cisco devices

Answer 5

Hardware calendar

Question 6

T/F: Hardware calendar is considered an authoritative source

Answer 6

F

Internal hardware clock of a device will drift over time, so it is not the ideal source

Question 7

What does an asterisk in front of the output of sh clock mean?

Answer 7

The time is not considered authoritative

Question 8

What is the most important reason to have an accurate time on a device?

Answer 8

Accurate log keeping for troubleshooting purposes

Question 9

What is the command to view a device’s logs

Answer 9

sh logging

Question 10

What is the command to manually configure the time on a Cisco device

Answer 10

clock set

Question 11

What config mode do you need to be in for clock commands

Answer 11

Priviledged EXEC mode

Question 12

What is the command to manually configure the hardware clock (aka calendar)

Answer 12

calendar set

Question 13

T/F: You never want the calendar and the clock on a device synchronized

Answer 13

F

It is always a good idea for the calendar and the clock to be synchronized

Question 14

What is the command to view a device’s hardware clock

Answer 14

sh calendar

Question 15

What is the command to sync a device’s calendar to its clock time

Answer 15

clock update-calendar

Question 16

What is the command to sync a device’s clock to the calendar time

Answer 16

clock read-calendar

Question 17

What is the command to configure the time zone on a Cisco device

Answer 17

clock timezone

Question 18

T/F: Timezone must be configured from global config mode since it is part of the device’s running config

Answer 18

T

Question 19

T/F: Timezone must be configured from priviledged EXEC mode since it is not part of the device’s running config

Answer 19

F

Timezone is part of the running config and therefore has to be changed in global config mode

Question 20

What is the command to enable daylight savings time automatic adjustment

Answer 20

clock summer-time (timezone) recurring (day to switch) (day to switch back)

Question 21

NTP prevents us from having to manually configure _____

Answer 21

time on devices connected to the network

Question 22

T/F: NTP doesn’t prevent device clocks from drifting and becoming out of sync

Answer 22

F

Part of NTP’s purpose is to provide clock synchronization across multiple devices

Question 23

T/F: It is possible for a device to become an NTP server and an NTP client at the same time

Answer 23

T

Question 24

Generally, NTP provides an accuracy of within _____ if the NTP server is in the same LAN

Answer 24

~1 millisecond

Question 25

Generally, NTP provides an accuracy of within _____ if the NTP server is over a WAN or the internet

Answer 25

~50 milliseconds

Question 26

What is the distance of an NTP server from the original reference clock referred to as

Answer 26

Stratum

Question 27

The farther away from a reference clock, the higher the ______ of the server

Answer 27

stratum

Question 28

T/F: A reference clock is stratum 0 within the NTP hierarchy

Answer 28

T

Question 29

What is a reference clock?

Answer 29

A very accurate timekeeping device like an atomic clock or a GPS clock

Question 30

Describe a stratum 1 NTP server

Answer 30

An NTP server that is directly connected to a reference clock

Question 31

T/F: Cisco devices generally can't get their time from a stratum 0 source

Answer 31

T Cisco devices generally need to be connected to a stratum 1 or higher source

Question 32

T/F: A stratum 2 server is directly connected to a stratum 1 server and gets its time from the stratum 1 server

Answer 32

T Stratum 2 servers get their time from stratum 1 servers

Question 33

T/F: A stratum 3 server is directly connected to a stratum 0 server and gets its time from the stratum 0 server

Answer 33

F Stratum 3 servers get their time from a stratum 2 server

Question 34

What is the maximum stratum before an NTP server is considered unreliable

Answer 34

Stratum 15

Question 35

T/F: NTP devices can peer with devices at the same stratum to provide a more accurate time and redundancy

Answer 35

T

Question 36

When an NTP server is peered with another NTP server on the same stratum, it is referred to as being in ______

Answer 36

symmetric active mode

Question 37

T/F: A Cisco device cannot be in server, client, and symmetric active mode (all 3) at the same time

Answer 37

F Cisco devices can operate in all 3 modes

Question 38

T/F: An NTP client cannot sync to multiple servers at the same time

Answer 38

F An NTP client can sync to multiple NTP servers

Question 39

NTP servers which get their time directly from reference clocks are referred to as _____

Answer 39

primary servers

Question 40

Define an NTP primary server

Answer 40

One which is directly connected to a reference clock

Question 41

T/F: Stratum 1 servers can also be called secondary servers

Answer 41

F They could be called primary servers

Question 42

NTP servers which get thier time from other NTP servers are called ____

Answer 42

Secondary servers

Question 43

Secondary servers operate in both ____ and ____ modes at the same time

Answer 43

Client, server

Question 44

NTP servers with stratum 2 and above are ____

Answer 44

secondary servers

Question 45

What is the command to add an NTP server to a Cisco device?

Answer 45

**ntp server** *ip-address*

Question 46

What is the command to manually have a Cisco device prefer a certain NTP server?

Answer 46

**ntp server** *ip-address* **preferred**

Question 47

What is the command to view NTP servers for a Cisco device?

Answer 47

**sh ntp associations**

Question 48

What is the command to get an overview of the NTP configuration on a Cisco device

Answer 48

**sh ntp status**

Question 49

T/F: NTP uses only the UTC time zone. To compensate, the time zone must be configured on the individual device

Answer 49

T

Question 50

What is the command to configure a router to update the hardware clock with the time learned via NTP

Answer 50

**ntp update-calendar**

Question 51

T/F: Normally, it is a bad idea to configure all devices to sync to public NTP servers in a small network

Answer 51

F Best practice is to use public NTP servers for small networks. NTP servers are only needed for larger enterprise networks

Question 52

What is the command to change the source interface for NTP messages on a Cisco router?

Answer 52

**ntp source** *interface*

Question 53

Why is is best practice to configure the NTP source int as a loopback int?

Answer 53

Since loopbacks can't physically fail, there is no possibility for an interface failure to cause a device to loose its NTP connection. tl;dr reduces failure probability

Question 54

After manually configuring the system clock and issuing the **ntp server 1.1.1.1** command, what should be done to complete a basic NTP client configuration?

Answer 54

Nothing, the basic configuration is complete.

Question 55

Issuing the **ntp server** command from global config mode enables ______

Answer 55

NTP static client mode

Question 56

R1 is connected to a subnet of NTP stratum 1 servers on its g0/0 interface. We want to configure R1 to receive its time from any NTP server on this connected subnet. What command should be issued?

Answer 56

**ntp broadcast client** on g0/0

Question 57

TOCK is an NTP stratum 2 server with the IP address 10.255.0.1 We want to configure R1 to synchronize its time from TOCK. What command should be issued to accomplish this?

Answer 57

**ntp server 10.255.0.1**

Question 58

R1 is configured to synchronize its time from TOCK, a stratum 2 NTP server. We want to configure R1 to act as an NTP server for its connected devices, while R1 still synchronizes with TOCK. What command should be issued to accomplish this?

Answer 58

**ntp master 3** R1 gets its time from TOCK, a stratum 2 server, so it is therefore stratum 3

Question 59

Issuing the **ntp peer** command from global config mode enables _____

Answer 59

NTP symmetric active mode