How to Check Clock Synchronisation between Oracle Cluster Nodes

cluvfy comp clocksync [-n <node_list>] [-noctss] [-verbose]

USAGE:
cluvfy comp clocksync [-n <node_list>] [-noctss] [-verbose]
<node_list> is the comma-separated list of non-domain qualified node
names on which the test should be conducted. If "all" is specified, 
then all the nodes in the cluster will be used for verification.

-noctss does not check Oracle Cluster Synch service, but checks only
the platforms native clock synch service(such as NTP)

DESCRIPTION:
Checks Oracle Cluster Time Synchronization Service(CTSS) on all nodes
in the nodelist. 

If no '-n' option is provided, local node is used for this check.  
If the "-noctss" option is specified, then Oracle CTSS check is not 
performed, instead the platforms native Time Synchronization is 
checked.

$ cluvfy comp clocksync

Verifying Clock Synchronization ...
CTSS is in Observer state. Switching over to clock synchronization 
checks using NTP

Verifying Network Time Protocol (NTP) ...
Verifying '/etc/chrony.conf' ...PASSED
Verifying Daemon 'chronyd' ...PASSED
Verifying NTP daemon or service using UDP port 123 ...PASSED
Verifying chrony daemon is synchronized with at least one external 
                  time source ...PASSED
Verifying Network Time Protocol (NTP) ...PASSED
Verifying Clock Synchronization ...PASSED

Verification of Clock Synchronization across the cluster nodes was 
    successful.

CVU operation performed:Clock Synchronization across the cluster nodes
Date: 03/09/2018 3:31:04 PM
CVU home: /u01/app/12.2.0.1/grid/
User: grid

$ cluvfy comp clocksync -n all -verbose

Verifying Clock Synchronization ...
Node Name Status
--------- ------------------------
racnode1  passed
racnode2  passed

Node Name State
--------- ------------------------
racnode1 Observer
racnode2 Observer

CTSS is in Observer state. 
Switching over to clock synchronization checks using NTP

Verifying Network Time Protocol (NTP) ...
Verifying '/etc/chrony.conf' ...
Node Name File exists?
--------- ------------------------
racnode1 yes
racnode2 yes

Verifying '/etc/chrony.conf' ...PASSED
Verifying Daemon 'chronyd' ...
Node Name Running?
--------- ------------------------
racnode1 yes
racnode2 yes

Verifying Daemon 'chronyd' ...PASSED
Verifying NTP daemon or service using UDP port 123 ...
Node Name Port Open?
--------- ------------------------
racnode1 yes
racnode2 yes

Verifying NTP daemon or service using UDP port 123 ...PASSED
Verifying chrony daemon is synchronized with at least one external 
                                       time source ...PASSED
Verifying Network Time Protocol (NTP) ...PASSED
Verifying Clock Synchronization ...PASSED

Verification of Clock Synchronization across the cluster nodes 
was successful.

CVU operation performed:Clock Synchronization across the cluster nodes
Date: 03/09/2018 3:35:14 PM
CVU home: /u01/app/12.2.0.1/grid/
User: grid