# which echo
# crontab -e
23 14 * * * /bin/echo hello
# crontab -l (Verify)

see explanation below.
Explanation
system-config-authentication
LDAP Server: ldap//instructor.example.com (In domain form, not write IP) OR
# yum groupinstall directory-client (1.krb5-workstation 2.pam-krb5 3.sssd)
# system-config-authentication
1.User Account Database: LDAP
2.LDAP Search Base DN: dc=example,dc=com
3.LDAP Server: ldap://instructor.example.com (In domain form, not write IP) 4.Download CA Certificate
5.Authentication Method: LDAP password
6.Apply
getent passwd ldapuser40

Answer see in the explanation.
Explanation/Reference:
Graphical Interfaces:
System-->Administration-->Date & Time
OR
# system-config-date

see explanation below.
Explanation
yum install -y autofs
mkdir /home/rehome
* /etc/auto.master
/home/rehome/etc/auto.ldap
Keep then exit
cp /etc/auto.misc /etc/auto.ldap
* /etc/auto.ldap
ldapuserX -fstype=nfs,rw server.domain11.example.com:/home/guests/
Keep then exit
systemctl start autofs
systemctl enable autofs
su - ldapuserX// test
If the above solutions cannot create files or the command prompt is -bash-4.2$, it maybe exist multi-level directory, this needs to change the server.domain11.example.com:/home/guests/ to server.domain11.example.com:/home/guests/ldapuserX. What is multi-level directory? It means there is a directory of ldapuserX under the /home/guests/ldapuserX in the questions. This directory is the real directory.

see explanation below.
Explanation
below
* iptables -F
* service iptables save
* iptables -A INPUT -s 172.25.0.0/16 -j REJECT
* service iptables save
* service iptables restart