Why was the network device with onboot=off specified in kickstart activated with dhcp during installation in Red Hat Enterprise Linux ?

Issue

• I want to install Red Hat Enterprise Linux on a machine with multiple network devices.
• I specified the network information in boot parameter to get the kickstart file from remote.

hostname=testmachine.example.com ip=192.168.120.100 netmask=255.255.255.0 gateway=192.168.120.1 nameserver=192.168.120.1 net.ifnames=0

• And, I disabled any other network devices except for the first network device eth0 in kickstart file. --activate option is not specified, and --onboot=off is specified.

network  --bootproto=dhcp --device=eth1 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth2 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth3 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth4 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth5 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth6 --onboot=off --noipv6 --noipv4
network  --bootproto=dhcp --device=eth7 --onboot=off --noipv6 --noipv4

• But, eth1 was activated with dhcp during installation. Why does it happen?