I was told that this configuration (which contains an error in DNS mask which is /23 instead of /24) works only because it's a SHARED bus. If it was a SWITCHED lan, the DNS responses from DNS to A wouldn't "be forwarded". Why?
Basically A, in order to communicate with DNS, has to pass THROUGH the DG (default gateway) because A sees the DNS address in another subnet. On the other hand, the DNS sees A in his same subnet (since IP A is inside DNS /23) so DNS "talks" directly (dest macaddress is A instead of DG so it's a direct communication) with A WITHOUT passing through DG.
I was told that this only works because the lan is a shared bus. If it was a switched lan the DNS response wouldn't be forwarded(????) Why? What does it mean? What's the issue?