Cisco DHCP Server Configuration
Router#conf t
Router(config)#ip dhcp pool POOL_NAME
Router(dhcp-config)#network 192.168.10.0 255.255.255.0
[This will create a DHCP pool]
Router(dhcp-config)#default-router 192.168.10.1
[This IP is the Gateway Address]
Router(dhcp-config)#dns-server 100.100.100.1
[This IP is the DNS Server IP]
If you want to add another ip block then create another pool
Router(config)#ip dhcp pool POOL_NAME1
Router(dhcp-config)#network 192.168.11.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.11.1
Router(dhcp-config)#dns-server 10.10.10.1
If you want to dissallow some ip address
Router(config)#ip dhcp excluded-address 192.168.10.1 192.168.10.10
[It will block ip 192.168.10.1 to 192.168.10.10]
If you want to dissallow a single IP
Router(config)#ip dhcp excluded-address 192.168.10.10
[It will block only one ip to 192.168.10.10]