Error :-
While starting crs / Adding the node the crs alert log will show the error ORA-21561 : OID generation failed
Solution:-
This is due to misconfiguration in following files,
1. /etc/hosts file is not having proper entries i.e localhost and the IP address that should resolve to dns and local
2. /etc/resolv.conf should have match in all nodes
2. /etc/resolv.conf should have match in all nodes
3.Check hostname and ipaddress be correct in all nodes