DCA

st0 {
        unit 1 {
            family inet {
                address 192.168.100.1/30;
            	}            
	    family inet6;
        }
        unit 2 {
            family inet {
                address 192.168.200.1/30;
            	}           
            family inet6;
        }

-------------------------------------------------------------
TC

st0 {
        unit 1 {
            family inet {
                address 192.168.100.2/30;
            	}            
	    family inet6;
        }
        unit 2 {
            family inet {
                address 192.168.200.2/30;
            	}           
            family inet6;
        }
------------------------------------------------------------
BOTH

protocols {
    ospf {
        area 0.0.0.10 {….
    			interface ge-0/0/7.0 {
        passive;
        }
    }
    stp;
}

---------------------------------------------------------------

QUESTION: 

security-zone untrust {
            screen untrust-screen;
            interfaces {….
                ge-0/0/0.0
		protocols {
                            ospf;
                            igmp;
				}
                ge-0/0/1.0
		protocols {
                            ospf;
                            igmp;
           			}
		}
}