If you find any warning message whenever you restart nginx server process as follows:

    Restarting nginx daemon: nginxRemaining processes: 16546
    nginx: [warn] conflicting server name "111.122.144.111" on 111.122.144.111:80, ignored
    nginx: [warn] conflicting server name "111.122.144.111" on 111.122.144.111:80, ignored
    nginx: [warn] conflicting server name "111.122.144.111" on 111.122.144.111:80, ignored
    nginx: [warn] conflicting server name "111.122.144.111" on 111.122.144.111:80, ignored
    nginx: [warn] conflicting server name "111.122.144.111" on 111.122.144.111:80, ignored
    nginx: [warn] conflicting server name "198.74.122.112" on 198.74.122.112:80, ignored

    Then follow the steps to instantly fix such issue:

        cd /etc/nginx/vhosts
        perl -pi -w -e 's/server_name(.*) Replace_With_IP_Address_Here/server_name$1/g;' *
        /etc/init.d/httpd restart