Assume that, if you are working in Data Center or running your application in VPS server, we can change static IP Address without downtime and reboot your Server.

Do carefully when update or changes in network configure file.

Check your current IP address pointing to the server,

​#  ifconfig


eth0      Link encap:Ethernet  HWaddr DF:BB:DD:CE:21:15

          inet addr:192.168.0.1 Bcast:192.168.3.3  Mask:255.255.255.0

          inet6 addr: ae40::226:3abb:fe9e:4af2/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:11333949 errors:0 dropped:0 overruns:0 frame:0

          TX packets:111301 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:6545516345 (2.7 GiB)  TX bytes:12362212 (33.9 MiB)

          Interrupt:11



lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:286 errors:0 dropped:0 overruns:0 frame:0

          TX packets:286 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:23628 (23.0 KiB)  TX bytes:23628 (23.0 KiB)


Before make changes  in configure file, keep a backup of eth0 original   file as "ifcfg-eth0".

Now update static IP address, NETMASK, BROADCAST, GATEWAY.
          
Your network device name is "eth0" so open configure file,
 
#  vim /etc/sysconfig/network-scripts/ifcfg-eth0


TYPE=Ethernet

DEVICE=eth0

IPADDR=192.168.1.100

NETMASK=255.255.255.0

BROADCAST=192.168.112.255

NETWORK=192.168.1.0

ONBOOT=yes

GATEWAY=192.168.1.1

UUID="37cf6cd6-6672-4eec-a1a6-6feb49b7bba5"

PREFIX=24

IPV6INIT=no

HWADDR=DF:BB:DD:CE:21:15

Once update static IP address ensure everything is correct in "ifcfg-eth0" file before save.



Finally restart your Network Service,
 
# /etc/init.d/network restart


Shutting down interface eth0:           [  OK  ]

Shutting down loopback interface:       [  OK  ]

Bringing up loopback interface:         [  OK  ]

Bringing up interface eth0:             [  OK  ]


Update Static IP Address in UI

Go to System -> Preferences -> Network Connections
 
-> Click On "Wired" Menu 
-> Click on "Add" 
-> Click on "IPV4 Settings" 

Fill the IP Address, Netmask, Gateway and DNS Servers. Restart your network service.
 
#  /etc/init.d/network restart