EX3400 is using ELS-style config. Example below:
jh@fw# show forwarding-options dhcp-relay { server-group { dhcp-server { 1.2.3.4; } } active-server-group dhcp-server; group dhcp-server { interface irb.10; interface irb.20; } } jh@fw# show forwarding-options | display set set forwarding-options dhcp-relay server-group dhcp-server 1.2.3.4 set forwarding-options dhcp-relay active-server-group dhcp-server set forwarding-options dhcp-relay group dhcp-server interface irb.10 set forwarding-options dhcp-relay group dhcp-server interface irb.20