If k is a foreign key in relation r1, then
? every tuple of r1 has adistinct value for k.
? k cannot have a nullvalue for tuples in r1.
? k is a key for someother relation.
? k is a primary key forr1.

Suppose a router has built up the routing table shown in the table. subnet number 128.96.39.00 28.96.39.128 128.96.40.00 192.4.153.0 default) subnet mask 255.255.255.128 255.255.255.128 255.255.255.128 255.255.255.192 nexthop interface 0 interface 1 r2 r3 r4. the router can deliver packets directly over interfaces 0 and 1, or it can forward packets to routers r2, r3, or r4. describe what the router does with a packet addressed to each of the following destinations: (a) 128.96.39.10 (b) 128.96.40.12 (c) 128.96.40.151 (d) 192.4.153.17 (e) 192.4.153.90