問題文
A pair of systems is being set up so that calls cross a firewall between them. What does the firewall see of the connections between that pair of systems?
選択肢
- No connections at all until an endpoint registers, since a pair of this kind carries the calls of registered devices and of nothing else on the network.
- Every one of them raised from the inside of the firewall outwards, since the outer system asks the inner one to raise whatever connections it is that a call needs.
- Connections raised in each direction in turn, since the media and the signaling of one call are handled by the two systems apart from one another.
- Every one of them raised from the outside of the firewall inwards, since the outer system is the one that learns of a call first and has to pass it along at once.