CCNA 200-301 v1.1 reference — IP Services

NTP client and server

NTP strata and peering, configure a device as client and server, and verify synchronization state and associations.

Objective 4.2v1.1 exam target

Transport

UDP 123

Stratum 0

Reference clock (GPS/atomic)

Stratum 1

Server synced to stratum 0

Poll interval

64 s default, varies with stability

Sync indicator

'synchronized' / * peer in associations

Symbol	Meaning
*	Synchronized to this peer — the selected time source
+	Surviving candidate — usable backup
-	Discarded — failed selection
x	Falseticker — rejected as unreliable
.	Excess peer — not used

NTP client and server

Sync to an upstream NTP server and serve time to the LAN — Privileged EXEC → Global configuration

Cisco IOS / IOS XE

configure terminal
ntp server 192.168.10.10
ntp master 4
 end

Verify

show ntp status
show ntp associations
show clock

ntp master makes the device itself a server at the given stratum — a lab/local fallback when no better source exists, not a routine necessity; a normal client can also serve downstream clients once synchronized.
Initial synchronization takes several minutes — don't judge failure too early.

Changes device configuration.

$ show ntp associations (interpreted)

address ref clock st when poll reach delay offset dispPeer address, its source, stratum and health metrics.

* 192.168.10.10 .GPS. 2 23 64 377 1.2 -3.1 2.8* = selected sync source; stratum 3 here (server's st 2 + 1).

+ 192.168.10.11 192.168.10.10 3 45 64 377 2.0 5.4 3.0+ = surviving candidate, not selected.

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Targets CCNA 200-301 v1.1 objectives. Supplemental blocks are labeled beyond exam scope.