The chage command can change the following parameters related to user password expiry and aging:
* The last password change date (-d or --lastday option)
* The password expiry date (-E or --expiredate option)
* The minimum number of days between password changes (-m or --mindays option)
* The maximum number of days during which a password is valid (-M or --maxdays option)
* The number of days of warning before password expires (-W or --warndays option) The chage command cannot change the number of days of inactivity after a password has expired before the account is locked. This parameter is controlled by the -I or --inactive option of the usermod command, which modifies the user account information. The chage command only displays the current value of this parameter, but does not allow changing it. References:
* chage command in Linux with examples - GeeksforGeeks
* 10 chage command examples in Linux [Cheat Sheet] - GoLinuxCloud
* How to Use the Chage Command in Linux - TecAdmin
* How to Manage User Password Expiration and Aging in Linux - Tecmint

The keywords dns and files can be used in the /etc/nsswitch.conf file to specify a source for host name lookups. The keyword dns means that the system will use the Domain Name System (DNS) to resolve host names to IP addresses. The keyword files means that the system will use the local /etc/hosts file to resolve host names to IP addresses. The order of the keywords on the line determines the order in which the sources will be queried. For example, the following line in /etc/nsswitch.conf:
hosts: files dns
means that the system will first check the /etc/hosts file for a matching host name, and if not found, it will query the DNS servers configured in /etc/resolv.conf. The other keywords in the question are not valid for the hosts database. The keyword resolv is used for the services database, which contains network service names and port numbers. The keyword remote is not a standard keyword, but it may be used by some applications to implement their own name service providers. The keyword hosts is the name of the database itself, not a source for it. Reference:
[LPI Linux Administrator - Exam 102 Objectives - Topic 109: Networking Fundamentals] nsswitch.conf(5) - Linux manual page What is the /etc/nsswitch.conf file in Linux - TecAdmin

The statement hosts: files dns is valid in the file /etc/nsswitch.conf. It means that the system will use the local
/etc/hosts file and the Domain Name System (DNS) to resolve host names to IP addresses. The order of the sources on the line determines the order in which they will be queried. In this case, the system will first check the /etc/hosts file for amatching host name, and if not found, it will query the DNS servers configured in
/etc/resolv.conf. The other statements in the question are not valid in the /etc/nsswitch.conf file. The statement multi on is not a valid keyword or source for any database. The statement 192.168.168.4 dns-server is not a valid syntax for specifying a source or an action. The statement include /etc/nsswitch.d/ is not a valid way to include another file or directory in the /etc/nsswitch.conf file. References:
* [LPI Linux Administrator - Exam 102 Objectives - Topic 109: Networking Fundamentals]
* nsswitch.conf(5) - Linux manual page
* What is the /etc/nsswitch.conf file in Linux - TecAdmin

server
Explanation:
The server option is used to configure a persistent association with a remote server or peer. It takes an argument that is either a host name or a numeric IP address of the NTP server. The ntpd daemon will periodically send NTP packets to the specified server and adjust the local clock according to the received responses. Multiple server options can be used to specify more than one NTP source. For example, the following lines in the /etc/ntp.conf file configure four external NTP sources:
server 0.asia.pool.ntp.org
server 0.oceania.pool.ntp.org
server 0.europe.pool.ntp.org
server 0.north-america.pool.ntp.org
Reference:
https://docs.ntpsec.org/latest/ntp_conf.html
https://vceguide.com/which-option-in-the-etc-ntp-conf-file-specifies-an-external-ntp-source-to-be-queried-for-time-information-2/
https://vceguide.com/which-option-in-the-etcntp-conf-file-specifies-an-external-ntp-source-to-be-queried-for-time-information/