Centos and Ubuntu Linux distributions to assign ip address automatically to a client machine. How Does dhcp work?

ethernets
, 
enp0s3
, and comment out static IP related configs:
network:
version: 2
renderer: networkd
ethernets:
ens0:
dhcp4: yes
Save the changes and run the following command to effect the changes.
$ sudo netplan apply 
For more information, see the 
dhcpd
and 
dhcpd.conf
man pages.
$ man dhcpd
$ man dhcpd.conf

Examples
# Servers subnet
subnet 192.168.11.0 netmask 255.255.255.0 {
range 192.168.11.1 192.168.11.251;
# 192.168.11.252 reserved for DHCP server
# 192.168.11.253 reserved for DNS server
# 192.168.11.254 reserved for router interface
option routers 192.168.11.254;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.11.253;
# default lease = 90 days, max lease = 120 days
default-lease-time 7776000;
max-lease-time 10368000;
}
# Staff subnet 1
subnet 192.168.12.0 netmask 255.255.255.0 {
range 192.168.12.1 192.168.12.253;
# 192.168.12.254 reserved for router interface
option routers 192.168.12.254;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.11.253;
# default lease = 30 days, max lease = 45 days
default-lease-time 2592000;
max-lease-time 3888000;
}
# Staff subnet 2
subnet 192.168.13.0 netmask 255.255.255.0 {
range 192.168.13.1 192.168.13.253;
# 192.168.13.254 reserved for router interface
option routers 192.168.13.254;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.11.253;
# default lease = 30 days, max lease = 45 days
default-lease-time 2592000;
max-lease-time 3888000;
}
# Staff subnet
subnet 192.168.15.0 netmask 255.255.255.0 {
range 192.168.15.1 192.168.15.253;
# 192.168.15.254 reserved for router interface
option routers 192.168.15.254;
option subnet-mask 255.255.255.0;
option domain-name-servers 192.168.11.253;
# default lease = 12 hrs, max lease = 24 hrs
default-lease-time 43200;
max-lease-time 86400;
}