1. Go to enable mode:
enable

2. Now we need to switch to configuration mode:
config terminal

3. First we define the ip address which will not be dhcp lease:
ip dhcp excluded-address 10.10.N.1 10.10.N.239
ip dhcp excluded-address 10.10.N.251 10.10.N.254

4. Create dhcp pool:
ip dhcp pool DHCP-POOL
	network 10.10.N.0 255.255.255.0
	default-router 10.10.N.254
	dns-server 10.10.0.241
	domain-name ws.nsrc.org