We are setting up as DC4 as a dc for this setup

sudo tee /etc/consul.d/consul-server.json <<EOF
{
  "datacenter": "dc4",
  "server": true,
  "bootstrap_expect": 1
}
EOF

Ideal setup whould be 5 server setup so it will be helpfull during failover.
Bootstrap_expect should be changed based on number of servers.

Restart consul server:

service consul restart

service consul status

Once you restart consul server you will see Active as soon as you restart and see status

Where to Next?

To setup vagrant for Consul, joining nodes into a cluster, and interacting with the agent, check out: Use consul UI.