How to enable/disable DHCP of eth0 ifconfig eth0 dhcp start or ifconfig eth0 dhcp drop does not seem to work for Android.  Is there a way to enable/disable DHCP for eth0 via shell commands?
try this code in android 5.1

ifconfig eth0 up
dhcpcd eth0


OR (static)

ifconfig eth0 192.168.70.65 netmask 255.255.255.0 up


and now 

ndc network create 100
ndc network interface add 100 eth0
ndc network route add 100 eth0 192.168.70.0/24 (gateway)
ndc network route add 100 eth0 0.0.0.0/0 192.168.2.40 192.168.2.50
ndc resolver setnetdns 100 localdomain 192.168.2.40 192.168.2.50 (dns1 dns2)
ndc network default set 100