Cisco Certified Support Technician (CCST) Networking 100-150 Practice Test 29
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.”.
Question 281
A technician reviews the following issue: At the fictional Maplecrest Office during its network support shift, the team observes: A workstation shows fe80::7a4b on its IPv6 interface and a technician tries to route it as a globally reachable internet destination. Which action MOST directly resolves the reported issue?
- Calculate the /25 network by masking the last octet and choose 192.168.10.128 as the network ID.
- Use an assigned global unicast or properly routed address for off-link communication.
- Configure a default gateway address within the workstation's 192.168.60.0/26 subnet.
- Apply 255.255.255.224 and recalculate the subnet's network and broadcast boundaries.
Explanation
Correct Answer
B:Correct. In the fictional Maplecrest Office case, IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link. The specified corrective action, “Use an assigned global unicast or properly routed address for off-link communication.”, directly targets that condition. Evidence of resolution: The link-local address remains local while the global address reaches a remote IPv6 host.
Incorrect Answers
A:That action addresses a different network issue: A workstation uses 192.168.10.130/25 and the help desk claims its subnet network address is 192.168.10.0. The present fictional Maplecrest Office finding instead needs “Use an assigned global unicast or properly routed address for off-link communication.”, verified by “The link-local address remains local while the global address reaches a remote IPv6 host.”.
C:That action addresses a different network issue: A remote endpoint uses 192.168.60.18/26 with gateway 192.168.60.126 and cannot leave its LAN. The present fictional Maplecrest Office finding instead needs “Use an assigned global unicast or properly routed address for off-link communication.”, verified by “The link-local address remains local while the global address reaches a remote IPv6 host.”.
D:That action addresses a different network issue: An admin converts /27 to a mask of 255.255.255.0 and allocates too many clients to a tiny segment. The present fictional Maplecrest Office finding instead needs “Use an assigned global unicast or properly routed address for off-link communication.”, verified by “The link-local address remains local while the global address reaches a remote IPv6 host.”.
Question 282
An incident reviewer analyzes this observation: At the fictional Maplecrest Office during its network support shift, the team observes: A workstation shows fe80::7a4b on its IPv6 interface and a technician tries to route it as a globally reachable internet destination. What is the MOST specific underlying cause?
- IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link.
- The /25 boundary splits the /24 into 0–127 and 128–255, placing .130 in 192.168.10.128/25.
- The RFC 1918 private range spans 172.16.0.0 through 172.31.255.255, including 172.20.14.8.
- IPv4 127.0.0.0/8 is loopback to the local host, not a remote server reachable from peers.
Explanation
Correct Answer
A:Correct. This mechanism fits the observed network symptom at the fictional Maplecrest Office: IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link. The corresponding remedy is “Use an assigned global unicast or properly routed address for off-link communication.”. Confirmation: The link-local address remains local while the global address reaches a remote IPv6 host.
Incorrect Answers
B:That cause belongs to a different case: A workstation uses 192.168.10.130/25 and the help desk claims its subnet network address is 192.168.10.0. The observed fictional Maplecrest Office condition is specifically explained by “IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link.”.
C:That cause belongs to a different case: A branch device has 172.20.14.8 but a technician labels it public because every 172.x.x.x address is public. The observed fictional Maplecrest Office condition is specifically explained by “IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link.”.
D:That cause belongs to a different case: A developer uses 127.0.0.1 as the server address in an application deployed to other PCs on the LAN. The observed fictional Maplecrest Office condition is specifically explained by “IPv6 fe80::/10 is link-local scope and ordinarily works only on the local link.”.
Question 283
After an approved correction, the support team reviews: At the fictional Maplecrest Office during its network support shift, the team observes: A workstation shows fe80::7a4b on its IPv6 interface and a technician tries to route it as a globally reachable internet destination. The approved corrective action is: “Use an assigned global unicast or properly routed address for off-link communication.” 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.
- Concurrent clients access internet services and the NAT table tracks distinct translated sessions.
- The link-local address remains local while the global address reaches a remote IPv6 host.
Explanation
Correct Answer
D:Correct. This is the required observable acceptance evidence for “Use an assigned global unicast or properly routed address for off-link communication.” at the fictional Maplecrest Office. It demonstrates correction of the original cause: IPv6 fe80::/10 is link-local scope and ordinarily works only on the local 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-local address remains local while the global address reaches a remote IPv6 host.” for the fictional Maplecrest Office 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-local address remains local while the global address reaches a remote IPv6 host.” for the fictional Maplecrest Office case.
C:That result is evidence for a separate corrective action, “Configure an approved source NAT/PAT rule and verify outbound connection translations.”. It does not establish the intended outcome “The link-local address remains local while the global address reaches a remote IPv6 host.” for the fictional Maplecrest Office case.
Question 284
Before approving the action, review: At the fictional Maplecrest Office during its network support shift, the team observes: A workstation shows fe80::7a4b on its IPv6 interface and a technician tries to route it as a globally reachable internet destination. During “Use an assigned global unicast or properly routed address for off-link communication.”, which precaution MOST specifically prevents a related risk?
- Do not use the broader /24 network address when the configured interface is /25.
- Do not confuse the client's private source address with the public source observed after PAT.
- Do not advertise a fe80:: link-local address as an ordinary global internet route.
- Do not classify public DNS destinations as internal RFC 1918 hosts.
Explanation
Correct Answer
C:Correct. This precaution prevents a second fault while applying “Use an assigned global unicast or properly routed address for off-link communication.” at the fictional Maplecrest Office. The required protection is “Do not advertise a fe80:: link-local address as an ordinary global internet route.”; success still requires “The link-local address remains local while the global address reaches a remote IPv6 host.”.
Incorrect Answers
A:This caution is appropriate for a separate failure pattern: A workstation uses 192.168.10.130/25 and the help desk claims its subnet network address is 192.168.10.0. The principal adjacent risk here is controlled by “Do not advertise a fe80:: link-local address as an ordinary global internet route.”.
B:This caution is appropriate for a separate failure pattern: A shared office connects many private IPv4 clients to the internet but expects each to consume a separate public address despite a single ISP-facing IPv4. The principal adjacent risk here is controlled by “Do not advertise a fe80:: link-local address as an ordinary global internet route.”.
D: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 advertise a fe80:: link-local address as an ordinary global internet route.”.
Question 285
A technician reviews the following issue: At the fictional Quarry Municipal IT before a planned system change, the team observes: 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. Which action MOST directly resolves the reported issue?
- Configure an approved source NAT/PAT rule and verify outbound connection translations.
- Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.
- Recognize the shared address scope and confirm carrier NAT or dedicated public access requirements.
- Design an appropriate /30 segment when exactly two traditional IPv4 host addresses are needed.
Explanation
Correct Answer
B:Correct. In the fictional Quarry Municipal IT case, 2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation. The specified corrective action, “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”, directly targets that condition. Evidence of resolution: The production IPv6 interface uses an authorized prefix and examples retain the documentation address.
Incorrect Answers
A:That action addresses a different network issue: A shared office connects many private IPv4 clients to the internet but expects each to consume a separate public address despite a single ISP-facing IPv4. The present fictional Quarry Municipal IT finding instead needs “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”, verified by “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.”.
C:That action addresses a different network issue: 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 present fictional Quarry Municipal IT finding instead needs “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”, verified by “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.”.
D:That action addresses a different network issue: A branch requires two usable addresses for a point-to-point IPv4 link and selects /29 without considering the simpler conventional /30. The present fictional Quarry Municipal IT finding instead needs “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”, verified by “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.”.
Question 286
An incident reviewer analyzes this observation: At the fictional Quarry Municipal IT before a planned system change, the team observes: 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. What is the MOST specific underlying cause?
- 2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.
- With a /24 mask their network prefixes are different and communication normally needs Layer 3 forwarding.
- A /27 contains only 32 total IPv4 addresses and 30 conventional usable hosts; /26 provides 62 usable.
- 100.64.0.0/10 is shared address space commonly used for carrier-grade NAT rather than individually public internet addresses.
Explanation
Correct Answer
A:Correct. This mechanism fits the observed network symptom at the fictional Quarry Municipal IT: 2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation. The corresponding remedy is “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”. Confirmation: The production IPv6 interface uses an authorized prefix and examples retain the documentation address.
Incorrect Answers
B:That cause belongs to a different case: Two laptops use 192.168.2.20/24 and 192.168.3.20/24; the technician treats them as directly on-link because both addresses begin 192.168. The observed fictional Quarry Municipal IT condition is specifically explained by “2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.”.
C:That cause belongs to a different case: A site requests at least 50 usable IPv4 addresses and the trainee chooses a /27 because 32 looks close to 50. The observed fictional Quarry Municipal IT condition is specifically explained by “2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.”.
D:That cause belongs to a different case: 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 observed fictional Quarry Municipal IT condition is specifically explained by “2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.”.
Question 287
After an approved correction, the support team reviews: At the fictional Quarry Municipal IT before a planned system change, the team observes: 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 approved corrective action is: “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.” Which result BEST demonstrates success?
- The computed network and host range follow /27, not an assumed classful /24.
- Interface and routing documentation distinguish .1 from the reserved address at .255.
- Manual subnet calculation matches a trusted calculator for the /23 address.
- The production IPv6 interface uses an authorized prefix and examples retain the documentation address.
Explanation
Correct Answer
D:Correct. This is the required observable acceptance evidence for “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.” at the fictional Quarry Municipal IT. It demonstrates correction of the original cause: 2001:db8::/32 is reserved for documentation examples rather than publicly routed production allocation.
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 production IPv6 interface uses an authorized prefix and examples retain the documentation address.” for the fictional Quarry Municipal IT case.
B:That result is evidence for a separate corrective action, “Identify .1 as a valid default gateway host and .255 as the broadcast for the subnet.”. It does not establish the intended outcome “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.” for the fictional Quarry Municipal IT case.
C:That result is evidence for a separate corrective action, “Determine the network as 172.16.8.0 and broadcast as 172.16.9.255.”. It does not establish the intended outcome “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.” for the fictional Quarry Municipal IT case.
Question 288
Before approving the action, review: At the fictional Quarry Municipal IT before a planned system change, the team observes: 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. During “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.”, which precaution MOST specifically prevents a related risk?
- Do not use a /24 mask with a documented /27 prefix length.
- Do not decide that hosts share a subnet using only the first two IPv4 octets.
- 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.
Explanation
Correct Answer
C:Correct. This precaution prevents a second fault while applying “Keep 2001:db8:abcd:2::/64 in documentation and use a real assigned prefix for production.” at the fictional Quarry Municipal IT. The required protection is “Do not treat 2001:db8:: documentation space as a routable production IPv6 allocation.”; success still requires “The production IPv6 interface uses an authorized prefix and examples retain the documentation address.”.
Incorrect Answers
A:This caution is appropriate for a separate failure pattern: An admin converts /27 to a mask of 255.255.255.0 and allocates too many clients to a tiny segment. The principal adjacent risk here is controlled by “Do not treat 2001:db8:: documentation space as a routable production IPv6 allocation.”.
B:This caution is appropriate for a separate failure pattern: Two laptops use 192.168.2.20/24 and 192.168.3.20/24; the technician treats them as directly on-link because both addresses begin 192.168. The principal adjacent risk here is controlled by “Do not treat 2001:db8:: documentation space as a routable production IPv6 allocation.”.
D: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 treat 2001:db8:: documentation space as a routable production IPv6 allocation.”.
Question 289
A technician reviews the following issue: At the fictional Kestrel Regional Office in a technician onboarding review, the team observes: A student sees fd34:5:6::10 and labels it a global publicly reachable address merely because it is 128 bits long. Which action MOST directly resolves the reported issue?
- Replace client-side loopback targeting with the server's reachable interface name or address.
- Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.
- Apply 255.255.255.224 and recalculate the subnet's network and broadcast boundaries.
- Investigate the DHCP or static configuration path before relying on the link-local address for routed access.
Explanation
Correct Answer
B:Correct. In the fictional Kestrel Regional Office case, IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes. The specified corrective action, “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”, directly targets that condition. Evidence of resolution: The design uses ULA internally and chooses an appropriate global prefix for internet reachability.
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 Kestrel Regional Office finding instead needs “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”, verified by “The design uses ULA internally and chooses an appropriate global prefix for internet reachability.”.
C:That action addresses a different network issue: An admin converts /27 to a mask of 255.255.255.0 and allocates too many clients to a tiny segment. The present fictional Kestrel Regional Office finding instead needs “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”, verified by “The design uses ULA internally and chooses an appropriate global prefix for internet reachability.”.
D: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 Kestrel Regional Office finding instead needs “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”, verified by “The design uses ULA internally and chooses an appropriate global prefix for internet reachability.”.
Question 290
An incident reviewer analyzes this observation: At the fictional Kestrel Regional Office in a technician onboarding review, the team observes: A student sees fd34:5:6::10 and labels it a global publicly reachable address merely because it is 128 bits long. What is the MOST specific underlying cause?
- IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes.
- A /27 prefix corresponds to mask 255.255.255.224, yielding blocks of 32 addresses.
- For 192.168.40.0/24, .0 is the network ID, .255 is the directed broadcast, and .1 is a valid host.
- 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 Kestrel Regional Office: IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes. The corresponding remedy is “Classify the fd34:5:6::10 address as ULA and distinguish it from global unicast.”. Confirmation: The design uses ULA internally and chooses an appropriate global prefix for internet reachability.
Incorrect Answers
B:That cause belongs to a different case: An admin converts /27 to a mask of 255.255.255.0 and allocates too many clients to a tiny segment. The observed fictional Kestrel Regional Office condition is specifically explained by “IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes.”.
C:That cause belongs to a different case: A LAN router's 192.168.40.1/24 interface is documented as the segment broadcast destination rather than a valid host. The observed fictional Kestrel Regional Office condition is specifically explained by “IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes.”.
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 Kestrel Regional Office condition is specifically explained by “IPv6 fc00::/7 designates unique-local addressing, commonly represented by fd00::/8 prefixes.”.