Cisco Certified Support Technician (CCST) Networking 100-150 Practice Test 28
Question 270
An incident reviewer analyzes this observation: At the fictional Seabrook Bakery after a user reports a recurring problem, the team observes: A remote endpoint uses 192.168.60.18/26 with gateway 192.168.60.126 and cannot leave its LAN. What is the MOST specific underlying cause?
- In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127.
- The 192.168.0.0/16 block is RFC 1918 private addressing and is not routed as an ordinary public destination.
- 10.0.0.0/8 is the private IPv4 block regardless of the apparent decimal value of its octets.
- IPv6 does not use IPv4-style broadcast; multicast serves applicable group communication roles.
Explanation
Correct Answer
A:Correct. This mechanism fits the observed network symptom at the fictional Seabrook Bakery: In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127. The corresponding remedy is “Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.”. Confirmation: The endpoint can ARP for the gateway and reach an off-subnet test host.
Incorrect Answers
B:That cause belongs to a different case: A small-office PC uses 192.168.40.17 and a trainee proposes advertising it as a directly reachable address on the public internet. The observed fictional Seabrook Bakery condition is specifically explained by “In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127.”.
C:That cause belongs to a different case: An administrator sees 10.42.7.18 in a lab and calls it a globally assigned public IPv4 address because its first octet is small. The observed fictional Seabrook Bakery condition is specifically explained by “In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127.”.
D:That cause belongs to a different case: A technician expects IPv6 to send a subnet-wide broadcast address like 192.168.1.255 when contacting all local nodes. The observed fictional Seabrook Bakery condition is specifically explained by “In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127.”.
Question 271
After an approved correction, the support team reviews: At the fictional Seabrook Bakery after a user reports a recurring problem, the team observes: A remote endpoint uses 192.168.60.18/26 with gateway 192.168.60.126 and cannot leave its LAN. The approved corrective action is: “Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.” Which result BEST demonstrates success?
- The computed network and host range follow /27, not an assumed classful /24.
- The workstation reaches permitted internet services through the edge's public-side address without publishing a private route.
- The expanded address contains exactly eight 16-bit groups and round-trips to the short form.
- The endpoint can ARP for the gateway and reach an off-subnet test host.
Explanation
Correct Answer
D:Correct. This is the required observable acceptance evidence for “Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.” at the fictional Seabrook Bakery. It demonstrates correction of the original cause: In a /26, .18 is in 192.168.60.0–.63 while .126 is in a different subnet .64–.127.
Incorrect Answers
A:That result is evidence for a separate corrective action, “Use the configured /27 prefix and corresponding mask for the subnet calculation.”. It does not establish the intended outcome “The endpoint can ARP for the gateway and reach an off-subnet test host.” for the fictional Seabrook Bakery case.
B:That result is evidence for a separate corrective action, “Keep the workstation on its private LAN and use approved address translation or a secure remote-access design at the edge.”. It does not establish the intended outcome “The endpoint can ARP for the gateway and reach an off-subnet test host.” for the fictional Seabrook Bakery case.
C:That result is evidence for a separate corrective action, “Expand 2001:db8::5 into eight hextets with the correct number of zero groups.”. It does not establish the intended outcome “The endpoint can ARP for the gateway and reach an off-subnet test host.” for the fictional Seabrook Bakery case.
Question 272
Before approving the action, review: At the fictional Seabrook Bakery after a user reports a recurring problem, the team observes: A remote endpoint uses 192.168.60.18/26 with gateway 192.168.60.126 and cannot leave its LAN. During “Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.”, which precaution MOST specifically prevents a related risk?
- Do not treat 2001:db8:: documentation space as a routable production IPv6 allocation.
- Do not assume a 100.70.x.x WAN address is independently public and accepts inbound internet connections.
- Do not point a normal endpoint at an unreachable gateway from a different local subnet.
- Do not assume unique-local IPv6 prefixes are globally routed by internet providers.
Explanation
Correct Answer
C:Correct. This precaution prevents a second fault while applying “Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.” at the fictional Seabrook Bakery. The required protection is “Do not point a normal endpoint at an unreachable gateway from a different local subnet.”; success still requires “The endpoint can ARP for the gateway and reach an off-subnet test host.”.
Incorrect Answers
A:This caution is appropriate for a separate failure pattern: An IPv6 endpoint is configured with 2001:db8:abcd:2::9/64 for a lab and the technician expects it to be a publicly assigned production Internet prefix. The principal adjacent risk here is controlled by “Do not point a normal endpoint at an unreachable gateway from a different local subnet.”.
B:This caution is appropriate for a separate failure pattern: A guest Wi-Fi laptop shows 100.70.4.9 on the carrier-facing status page and the technician treats it as a customer-owned public IPv4 for inbound hosting. The principal adjacent risk here is controlled by “Do not point a normal endpoint at an unreachable gateway from a different local subnet.”.
D:This caution is appropriate for a separate failure pattern: A student sees fd34:5:6::10 and labels it a global publicly reachable address merely because it is 128 bits long. The principal adjacent risk here is controlled by “Do not point a normal endpoint at an unreachable gateway from a different local subnet.”.
Question 273
A technician reviews the following issue: At the fictional Lighthouse Research Annex during a physical cabling audit, the team observes: A branch requires two usable addresses for a point-to-point IPv4 link and selects /29 without considering the simpler conventional /30. Which action MOST directly resolves the reported issue?
- Replace client-side loopback targeting with the server's reachable interface name or address.
- Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.
- Distinguish public and private source scopes and identify the required boundary translation.
- Check neighbor solicitation and advertisement traffic for the IPv6 peer on the local link.
Explanation
Correct Answer
B:Correct. In the fictional Lighthouse Research Annex case, A conventional /30 yields four addresses with two usable host addresses for a small routed link. The specified corrective action, “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”, directly targets that condition. Evidence of resolution: The link's address plan lists two valid interface hosts between its network and broadcast addresses.
Incorrect Answers
A:That action addresses a different network issue: A developer uses 127.0.0.1 as the server address in an application deployed to other PCs on the LAN. The present fictional Lighthouse Research Annex finding instead needs “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”, verified by “The link's address plan lists two valid interface hosts between its network and broadcast addresses.”.
C:That action addresses a different network issue: A network drawing marks 8.8.8.8 and 192.168.1.10 as the same address-scope type for internet routing. The present fictional Lighthouse Research Annex finding instead needs “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”, verified by “The link's address plan lists two valid interface hosts between its network and broadcast addresses.”.
D:That action addresses a different network issue: An engineer expects an IPv6 host to ARP for a neighbor's MAC address exactly as IPv4 does. The present fictional Lighthouse Research Annex finding instead needs “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”, verified by “The link's address plan lists two valid interface hosts between its network and broadcast addresses.”.
Question 274
An incident reviewer analyzes this observation: At the fictional Lighthouse Research Annex during a physical cabling audit, the team observes: A branch requires two usable addresses for a point-to-point IPv4 link and selects /29 without considering the simpler conventional /30. What is the MOST specific underlying cause?
- A conventional /30 yields four addresses with two usable host addresses for a small routed link.
- An IPv4 169.254.0.0/16 link-local address often indicates automatic self-assignment when normal address configuration is unavailable.
- IPv6 :: compression represents a contiguous run of zero 16-bit groups and may appear only once in one address.
- 10.0.0.0/8 is the private IPv4 block regardless of the apparent decimal value of its octets.
Explanation
Correct Answer
A:Correct. This mechanism fits the observed network symptom at the fictional Lighthouse Research Annex: A conventional /30 yields four addresses with two usable host addresses for a small routed link. The corresponding remedy is “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”. Confirmation: The link's address plan lists two valid interface hosts between its network and broadcast addresses.
Incorrect Answers
B:That cause belongs to a different case: A receptionist reports 169.254.88.2 on a Windows laptop and the team tries to treat it as an ordinary assigned internet WAN address. The observed fictional Lighthouse Research Annex condition is specifically explained by “A conventional /30 yields four addresses with two usable host addresses for a small routed link.”.
C:That cause belongs to a different case: A student expands 2001:db8::5 into an address with two separate :: compression markers and too many hextets. The observed fictional Lighthouse Research Annex condition is specifically explained by “A conventional /30 yields four addresses with two usable host addresses for a small routed link.”.
D:That cause belongs to a different case: An administrator sees 10.42.7.18 in a lab and calls it a globally assigned public IPv4 address because its first octet is small. The observed fictional Lighthouse Research Annex condition is specifically explained by “A conventional /30 yields four addresses with two usable host addresses for a small routed link.”.
Question 275
After an approved correction, the support team reviews: At the fictional Lighthouse Research Annex during a physical cabling audit, the team observes: A branch requires two usable addresses for a point-to-point IPv4 link and selects /29 without considering the simpler conventional /30. The approved corrective action is: “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.” Which result BEST demonstrates success?
- The workstation reaches permitted internet services through the edge's public-side address without publishing a private route.
- An external site sees the approved edge public source while the workstation retains its private address.
- The design uses ULA internally and chooses an appropriate global prefix for internet reachability.
- The link's address plan lists two valid interface hosts between its network and broadcast addresses.
Explanation
Correct Answer
D:Correct. This is the required observable acceptance evidence for “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.” at the fictional Lighthouse Research Annex. It demonstrates correction of the original cause: A conventional /30 yields four addresses with two usable host addresses for a small routed link.
Incorrect Answers
A:That result is evidence for a separate corrective action, “Keep the workstation on its private LAN and use approved address translation or a secure remote-access design at the edge.”. It does not establish the intended outcome “The link's address plan lists two valid interface hosts between its network and broadcast addresses.” for the fictional Lighthouse Research Annex case.
B:That result is evidence for a separate corrective action, “Keep the private prefix internally and arrange approved NAT or public address allocation at the network edge.”. It does not establish the intended outcome “The link's address plan lists two valid interface hosts between its network and broadcast addresses.” for the fictional Lighthouse Research Annex case.
C:That result is evidence for a separate corrective action, “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”. It does not establish the intended outcome “The link's address plan lists two valid interface hosts between its network and broadcast addresses.” for the fictional Lighthouse Research Annex case.
Question 276
Before approving the action, review: At the fictional Lighthouse Research Annex during a physical cabling audit, the team observes: A branch requires two usable addresses for a point-to-point IPv4 link and selects /29 without considering the simpler conventional /30. During “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.”, which precaution MOST specifically prevents a related risk?
- Do not classify public DNS destinations as internal RFC 1918 hosts.
- Do not assume a 100.70.x.x WAN address is independently public and accepts inbound internet connections.
- Do not claim that a conventional /30 offers four usable host addresses.
- Do not replace a documented CIDR prefix with a historical classful default.
Explanation
Correct Answer
C:Correct. This precaution prevents a second fault while applying “Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.” at the fictional Lighthouse Research Annex. The required protection is “Do not claim that a conventional /30 offers four usable host addresses.”; success still requires “The link's address plan lists two valid interface hosts between its network and broadcast addresses.”.
Incorrect Answers
A:This caution is appropriate for a separate failure pattern: A network drawing marks 8.8.8.8 and 192.168.1.10 as the same address-scope type for internet routing. The principal adjacent risk here is controlled by “Do not claim that a conventional /30 offers four usable host addresses.”.
B:This caution is appropriate for a separate failure pattern: A guest Wi-Fi laptop shows 100.70.4.9 on the carrier-facing status page and the technician treats it as a customer-owned public IPv4 for inbound hosting. The principal adjacent risk here is controlled by “Do not claim that a conventional /30 offers four usable host addresses.”.
D:This caution is appropriate for a separate failure pattern: A trainee is told an old Class C IPv4 label requires a /24 mask even though a configured interface explicitly uses /27. The principal adjacent risk here is controlled by “Do not claim that a conventional /30 offers four usable host addresses.”.
Question 277
A technician reviews the following issue: At the fictional Summit Print Shop during a scheduled lab validation, the team observes: A LAN router's 192.168.40.1/24 interface is documented as the segment broadcast destination rather than a valid host. Which action MOST directly resolves the reported issue?
- Use ::/0 with the appropriate IPv6 next hop in the IPv6 routing table.
- Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.
- Investigate the DHCP or static configuration path before relying on the link-local address for routed access.
- Keep the private prefix internally and arrange approved NAT or public address allocation at the network edge.
Explanation
Correct Answer
B:Correct. In the fictional Summit Print Shop case, For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host. The specified corrective action, “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”, directly targets that condition. Evidence of resolution: Interface and routing documentation distinguish .1 from the reserved address at .255.
Incorrect Answers
A:That action addresses a different network issue: A router carries an IPv6 default route and a trainee writes it as 0.0.0.0/0 in the IPv6 route table. The present fictional Summit Print Shop finding instead needs “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”, verified by “Interface and routing documentation distinguish .1 from the reserved address at .255.”.
C:That action addresses a different network issue: A receptionist reports 169.254.88.2 on a Windows laptop and the team tries to treat it as an ordinary assigned internet WAN address. The present fictional Summit Print Shop finding instead needs “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”, verified by “Interface and routing documentation distinguish .1 from the reserved address at .255.”.
D:That action addresses a different network issue: A support analyst believes an internal 192.168.50.0/24 address can be made public solely by changing the router's default route. The present fictional Summit Print Shop finding instead needs “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”, verified by “Interface and routing documentation distinguish .1 from the reserved address at .255.”.
Question 278
An incident reviewer analyzes this observation: At the fictional Summit Print Shop during a scheduled lab validation, the team observes: A LAN router's 192.168.40.1/24 interface is documented as the segment broadcast destination rather than a valid host. What is the MOST specific underlying cause?
- For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.
- IPv6 :: compression represents a contiguous run of zero 16-bit groups and may appear only once in one address.
- 2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.
- 8.8.8.8 is publicly addressed while 192.168.1.10 belongs to private RFC 1918 space.
Explanation
Correct Answer
A:Correct. This mechanism fits the observed network symptom at the fictional Summit Print Shop: For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host. The corresponding remedy is “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”. Confirmation: Interface and routing documentation distinguish .1 from the reserved address at .255.
Incorrect Answers
B:That cause belongs to a different case: A student expands 2001:db8::5 into an address with two separate :: compression markers and too many hextets. The observed fictional Summit Print Shop condition is specifically explained by “For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.”.
C:That cause belongs to a different case: An IPv6 endpoint is configured with 2001:db8:abcd:2::9/64 for a lab and the technician expects it to be a publicly assigned production Internet prefix. The observed fictional Summit Print Shop condition is specifically explained by “For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.”.
D:That cause belongs to a different case: A network drawing marks 8.8.8.8 and 192.168.1.10 as the same address-scope type for internet routing. The observed fictional Summit Print Shop condition is specifically explained by “For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.”.
Question 279
After an approved correction, the support team reviews: At the fictional Summit Print Shop during a scheduled lab validation, the team observes: A LAN router's 192.168.40.1/24 interface is documented as the segment broadcast destination rather than a valid host. The approved corrective action is: “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.” Which result BEST demonstrates success?
- The annotation correctly allocates 64 bits to each part of the 128-bit address.
- The laptop later receives its intended LAN address and default gateway instead of only a 169.254.x.x value.
- The neighbor cache shows the resolved link-layer address after ICMPv6 discovery.
- Interface and routing documentation distinguish .1 from the reserved address at .255.
Explanation
Correct Answer
D:Correct. This is the required observable acceptance evidence for “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.” at the fictional Summit Print Shop. It demonstrates correction of the original cause: For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.
Incorrect Answers
A:That result is evidence for a separate corrective action, “Explain the /64 split between network prefix and interface identifier for the example subnet.”. It does not establish the intended outcome “Interface and routing documentation distinguish .1 from the reserved address at .255.” for the fictional Summit Print Shop case.
B:That result is evidence for a separate corrective action, “Investigate the DHCP or static configuration path before relying on the link-local address for routed access.”. It does not establish the intended outcome “Interface and routing documentation distinguish .1 from the reserved address at .255.” for the fictional Summit Print Shop case.
C:That result is evidence for a separate corrective action, “Check neighbor solicitation and advertisement traffic for the IPv6 peer on the local link.”. It does not establish the intended outcome “Interface and routing documentation distinguish .1 from the reserved address at .255.” for the fictional Summit Print Shop case.
Question 280
Before approving the action, review: At the fictional Summit Print Shop during a scheduled lab validation, the team observes: A LAN router's 192.168.40.1/24 interface is documented as the segment broadcast destination rather than a valid host. During “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”, which precaution MOST specifically prevents a related risk?
- Do not advertise RFC 1918 workstation addresses as globally routable internet prefixes.
- Do not classify public DNS destinations as internal RFC 1918 hosts.
- Do not confuse the first usable host with the subnet's broadcast address.
- Do not assume unique-local IPv6 prefixes are globally routed by internet providers.
Explanation
Correct Answer
C:Correct. This precaution prevents a second fault while applying “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.” at the fictional Summit Print Shop. The required protection is “Do not confuse the first usable host with the subnet's broadcast address.”; success still requires “Interface and routing documentation distinguish .1 from the reserved address at .255.”.
Incorrect Answers
A:This caution is appropriate for a separate failure pattern: A small-office PC uses 192.168.40.17 and a trainee proposes advertising it as a directly reachable address on the public internet. The principal adjacent risk here is controlled by “Do not confuse the first usable host with the subnet's broadcast address.”.
B:This caution is appropriate for a separate failure pattern: A network drawing marks 8.8.8.8 and 192.168.1.10 as the same address-scope type for internet routing. The principal adjacent risk here is controlled by “Do not confuse the first usable host with the subnet's broadcast address.”.
D:This caution is appropriate for a separate failure pattern: A student sees fd34:5:6::10 and labels it a global publicly reachable address merely because it is 128 bits long. The principal adjacent risk here is controlled by “Do not confuse the first usable host with the subnet's broadcast address.”.