What are the six mistakes that were made in the configuration of the following network? topology

I could only find 3. Since the subnet on the left has as HostMin and as HostMax, Host A4 and Host A5 cannot be in this subnet. Subnet A should also have the IP because it's a network address.

I can't seem to be able to find the other 3, what am I missing?


1 Answer 1


On a quick overview, I can find the following problems:

  1. The IP address for interface eth1 of the router is the network address for Subnet A While this generally works, there are some really ancient RFCs that prohibit the use of network addresses for hosts. Typically, the address of a router is either the first or the last host address in a network, in this case either or
  2. The same applies to the IP address for interface eth2 of the router, which is the network address of Subnet B Traditionally, the router address would either be or
  3. The IP address for interface eth0 of the router is within Subnet B Presumably, this is supposed to be the upstream interface to the rest of the world and would thus be in some public subnet, a DMZ, a transit subnet, or maybe an RFC 3021 Point-to-Point /31 subnet.
  4. The EUI-48 MAC address of Switch B 00-11-27-82-H3-E6 is not a valid hexadecimal number representation. Hexadecimal number representation only uses the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a / A, b / B, c / C, d / D, e / E, and f / F.
  5. The IP address of Host A4 is the broadcast address for Subnet A Broadcast addresses must not be used for hosts.
  6. The IP address of Host A5 is outside Subnet A
  • $\begingroup$ Thank you! Is subnet A having the IP-address and not (ending in zero) not considered a mistake? I thought network addresses should end in 0 to indicate that they're network and not host addresses. $\endgroup$
    – Karla
    Commented Mar 30, 2022 at 6:25
  • $\begingroup$ @Karla: I don't follow your question. does end in zero. $\endgroup$ Commented Mar 30, 2022 at 14:38

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