Components of TCP/IP Networks ICSSCADA Practice Questions (Page 7)

Questions 31–35

1. 31application · medium

   A network engineer is planning the IP addressing for a new OT network segment that will contain 30 field devices. The engineer wants to use a private IPv4 subnet that provides enough addresses for the devices and allows for some growth, while keeping the subnet as small as possible to limit broadcast domain size. Which subnet mask should be used?

   • A255.255.255.224 (/27)
   • B255.255.255.192 (/26)
   • C255.255.255.128 (/25)
   • D255.255.255.0 (/24)
   Reveal Solution Discussion Select an answer first
2. 32expert · medium

   A network administrator is planning the IP addressing for a new OT network that will have 200 devices. The administrator wants to use a private IPv4 subnet that provides enough addresses for the devices and allows for 50% growth, while keeping the subnet as small as possible to limit broadcast traffic. Which subnet mask should be used?

   • A255.255.252.0 (/22)
   • B255.255.255.128 (/25)
   • C255.255.255.0 (/24)
   • D255.255.254.0 (/23)
   Reveal Solution Discussion Select an answer first
4. 33expert · hard

   A senior network engineer is troubleshooting intermittent communication between a SCADA server and a remote substation. The SCADA server is on subnet 192.168.10.0/24, and the substation is on 192.168.20.0/24. The router connecting the two subnets has a route to 192.168.20.0/24 via a next-hop of 192.168.10.1. The SCADA server's default gateway is 192.168.10.1. The engineer observes that the SCADA server can ping the substation's gateway (192.168.20.1) but cannot ping the substation's PLC (192.168.20.5). What is the most likely cause?

   • AThe PLC is down or has a firewall blocking ICMP.
   • BThe SCADA server's ARP cache is missing the PLC's MAC address.
   • CThe PLC's default gateway is misconfigured.
   • DThe router does not have a route back to the SCADA server's subnet.
   Reveal Solution Discussion Select an answer first
5. 34expert · hard

   A utility company is migrating its SCADA network from IPv4 to IPv6. The migration team must ensure that legacy IPv4-only field devices can still communicate with the new IPv6 historian server during the transition. The network team has limited budget and wants to avoid deploying additional hardware. Which approach best meets these constraints?

   • AUse tunneling protocols like 6to4 to encapsulate IPv6 in IPv4 packets.
   • BConfigure the historian server with only an IPv6 address and use DNS to resolve names.
   • CDeploy a NAT64 gateway to translate IPv6 traffic to IPv4.
   • DUse dual-stack on the historian server and routers so both IPv4 and IPv6 traffic can be handled.
   Reveal Solution Discussion Select an answer first
6. 35application · medium

   A technician is troubleshooting connectivity between two PLCs on different subnets in a factory. The PLCs can reach their local default gateways, but traffic between them fails. The technician checks the routing table on the router and finds no route for the destination subnet. What is the most likely cause?

   • AThe switch is not forwarding broadcast frames between the subnets.
   • BThe PLCs are using UDP, which cannot cross routers.
   • CThe PLCs have incorrect MAC addresses configured.
   • DThe router has no route to the destination subnet, so it drops the packets.
   Reveal Solution Discussion Select an answer first