Cisco Certified Network Associate (CCNA) 200-301 Practice Test 11
Question 100
An IPv6 static route references link-local next hop `fe80::2`, which is not globally unique and must be associated with its outgoing link. After the route is corrected, which evidence most directly validates next-hop resolution?
- The route lists `fe80::2` alone without any interface on a multihomed router.
- `show ip route` reports a working IPv4 default gateway.
- An IPv6 Router Advertisement contains an unrelated global /64, but the static route next hop is not resolved.
- The route identifies the intended exit interface as well as `fe80::2`, and `show ipv6 neighbors` resolves `fe80::2` on that same interface.
Explanation
Correct Answer
D:An IPv6 link-local next hop can be repeated on different links. A static route using it must identify the egress interface, and the neighbor cache must resolve the router on that link. This tests the scoped route decision rather than global address reachability.
Incorrect Answers
A:The destination link is ambiguous from a bare link-local address; the interface scope must be specified for an unambiguous static next hop.
B:The IPv4 RIB does not verify the IPv6 link-local neighbor or egress scope.
C:A host-prefix advertisement does not establish neighbor reachability to the intended scoped link-local next hop.
Question 101
IPv6 hosts on VLAN 20 retain only link-local addresses after a router change. The router is intended to advertise `2001:db8:20:20::/64` for SLAAC. Following the fix, which capture-and-host evidence confirms that stateless global address autoconfiguration can occur?
- Router Advertisements include a valid Prefix Information Option for `2001:db8:20:20::/64` with the autonomous (A) flag set, and clients form addresses in that /64.
- Only Neighbor Solicitations for fe80:: destinations are seen, and clients continue to have link-local addresses.
- The router has a connected IPv6 /64 in its route table, but no Router Advertisement reaches the VLAN.
- A default IPv4 route is installed on the gateway, with no IPv6 prefix advertised.
Explanation
Correct Answer
A:For SLAAC, an IPv6 router advertises a usable prefix with the autonomous-address-configuration flag in the Prefix Information Option, and hosts generate global unicast addresses from it. A connected route by itself is not an RA. The advertised prefix, flags and actual host address are the decisive evidence.
Incorrect Answers
B:Neighbor Discovery and link-local addresses can work even when no usable SLAAC prefix is advertised. Seeing only fe80:: traffic would reproduce the reported symptom rather than prove the router-advertisement fix.
C:The IPv6 connected route shows a local layer-3 interface configuration, not that multicast RA messages reached clients or authorized autonomous configuration. An RA capture and host global address are still necessary.
D:An IPv4 route plays no part in IPv6 Router Advertisements or the autonomous flag. Without a valid advertised IPv6 /64, the original SLAAC failure remains.
Question 102
After restoring a missing IPv6 default route on R1, `show ipv6 route` now includes `S ::/0 via fe80::2, Gi0/1`. The upstream router should respond at that link-local next hop. Which combined post-change observation most directly validates that forwarding, not just a saved route line, can work?
- The LAN interface has a global IPv6 /64, without inspecting the upstream gateway.
- Client router-advertisement flags are correct, even if the upstream link is down.
- The default route is installed, fe80::2 resolves on Gi0/1 in IPv6 neighbors, and a probe to an external IPv6 literal succeeds.
- The IPv4 routing table has an installed 0.0.0.0/0 entry.
Explanation
Correct Answer
C:This verifies all three relevant layers: an installed ::/0 route, Layer 2 neighbor reachability for scoped fe80::2 on Gi0/1, and actual successful forwarding to an off-link IPv6 destination. A route display alone may hide neighbor-resolution faults.
Incorrect Answers
A:An IPv6 address on a LAN interface is necessary for local functions but does not show the router can resolve the default route next hop. The route and neighbor information for the upstream link must be checked separately.
B:Router-advertisement flags establish host autoconfiguration behavior on a local LAN. They do not establish that the router has a usable link-local neighbor for its IPv6 default egress path.
D:An IPv4 default route is evaluated in a separate address-family routing table and cannot provide IPv6 ::/0 forwarding. The test must inspect IPv6 routing and neighbor state.
Question 103
A designer must distinguish IPv6 global-unicast address space from RFC4193 unique-local addressing when choosing Internet-facing versus internal destinations. Which statement is technically correct?
- IPv6 global-unicast addresses are generally selected from `2000::/3`, while `fc00::/7` designates unique-local addresses that are not advertised on the public Internet.
- `fc00::/7` is the globally advertised Internet-unicast pool and `2000::/3` is only link-local.
- Every `2001:db8::/32` documentation address is assigned to a live public Internet host.
- IPv6 link-local `fe80::/10` is the usual source for traffic routed across the public Internet.
Explanation
Correct Answer
A:Global-unicast prefix classification and actual public reachability are not identical: an address can fall in a reserved/documentation subrange. ULA addresses are intended for local organizational routing, not direct public-Internet advertisement.
Incorrect Answers
B:Those classifications are reversed; link-local IPv6 uses fe80::/10.
C:2001:db8::/32 is reserved for examples, so membership within 2000::/3 does not guarantee public routability.
D:Link-local scope is one link and is not forwarded by routers as a global source.
Question 104
An application sends one IPv6 message to every subscribed receiver in a group. Another service advertises a single address from several nodes so normal unicast routing selects one instance. Which addressing distinction matches these behaviors?
- Use anycast for delivery to every joined listener and multicast for one nearest replica.
- Use the IPv6 unspecified address `::/128` as a multicast group for application fan-out.
- Use link-local `fe80::/10` for the shared global anycast destination on different routed sites.
- Use IPv6 multicast (`ff00::/8`) for group delivery and an anycast unicast-format address for routing to one of several instances.
Explanation
Correct Answer
D:Multicast identifies receivers joined to a group, whereas anycast allows several interfaces to share an address and the network forwards to an appropriate instance by unicast routing. Anycast does not imply replication to every replica.
Incorrect Answers
A:Those delivery semantics are reversed: multicast is group distribution, anycast is one-of-many selection.
B:The unspecified address is not a routable multicast destination; group destinations begin with ff00::/8.
C:Link-local addresses are scoped to individual links and do not provide a cross-site unicast anycast service.
Question 105
A router derives an IPv6 modified EUI-64 interface identifier from MAC address 00:1A:2B:3C:4D:5E. Which 64-bit identifier is formed after inserting FF:FE and inverting the U/L bit?
- 021A:2BFF:FE3C:4D5E
- 001A:2BFF:FE3C:4D5E, which fails to invert the U/L bit.
- 021A:2B3C:4D5E:0000, which omits the inserted FF:FE bytes.
- FFFE:001A:2B3C:4D5E, which places the inserted bytes at the front.
Explanation
Correct Answer
A:The 48-bit MAC address begins with octet 00. In modified EUI-64 construction, split the MAC into the first three bytes and the last three bytes, insert FF:FE between them, and toggle bit 0x02 in the first byte. Toggling 00 produces 02. The eight resulting bytes are 02:1A:2B:FF:FE:3C:4D:5E, grouped into IPv6 hextets as 021A:2BFF:FE3C:4D5E. This is an interface identifier, not a complete global IPv6 address; a network prefix must be combined with it for an address.
Incorrect Answers
B:Inserting FF:FE between the first three and last three MAC bytes is one required EUI-64 step, but the universal/local bit in the first byte must also be inverted. Leaving the first byte as 00 incorrectly keeps that bit unchanged. This answer shows the right insertion location with the wrong U/L transformation.
C:The proposed grouping lacks the mandatory FF:FE insertion between the original three-byte halves. Padding the original MAC address with zeros changes the identifier but is not the specified modified EUI-64 algorithm. A correct result contains eight bytes including the inserted FF and FE plus the inverted original first octet.
D:The algorithm does not prepend FF:FE to the original six-byte MAC address. It inserts the two bytes in the middle so the original vendor and device portions remain in their expected relative order. This alternative would yield a different 64-bit value even if its total length appears valid.
Question 106
A host uses only IPv6 unique-local address `fd12:3456:789a::10` and can reach internal ULA peers, but direct IPv6 connections to global Internet destinations fail. Which explanation fits its addressing constraints?
- The unique-local source is itself a globally advertised address and should traverse the Internet unchanged.
- The only problem is the host must form a MAC-based modified EUI-64 IID, regardless of its prefix.
- ULA source addresses are not globally routed; the host needs suitable global-unicast connectivity or a deliberate translation mechanism to reach public Internet services.
- The host must replace IPv6 with an IPv4 ARP broadcast because IPv6 cannot carry Internet traffic.
Explanation
Correct Answer
C:RFC4193 unique-local addresses are intended for internal routing and are not announced as normal global reachability on the public Internet. An internal ULA working does not imply a public path with globally usable source and return routing.
Incorrect Answers
A:ULA prefixes `fc00::/7` are not normal globally routed source addresses.
B:The IID construction technique cannot make an fc00::/7 source into globally routable address space.
D:IPv6 supports routed global Internet traffic when hosts have appropriate global addressing, routing and permitted policy.
Question 107
A network operator configures the same IPv6 unicast address on two service instances and advertises a route to that anycast destination from both sites. A client normally reaches the routing-preferred instance, but an operator expects every request to be copied to both and calls the single reply a multicast outage. Which misconception explains the report?
- The operator is confusing anycast with multicast: anycast normally forwards a unicast packet to one route-selected instance rather than copying it to all group members.
- The client lacks a default gateway because Router Advertisements are suppressed.
- The destination is a link-local IPv6 address and must not be routed beyond one link.
- The switch changed an 802.1Q native VLAN and reclassified the client traffic.
Explanation
Correct Answer
A:Anycast uses a shared unicast address at multiple destinations, with normal unicast routing choosing an available route-selected instance. It does not replicate one packet to every configured service. Multicast instead uses a multicast group destination and replication appropriate to group membership. The single reply is therefore expected for an anycast service and is not evidence of a multicast failure. Inspect the destination address class and installed routes to distinguish a unicast anycast design from multicast delivery.
Incorrect Answers
B:A missing default route can prevent a host reaching remote IPv6 services, but this client successfully receives a reply from a selected service instance. That evidence is inconsistent with a universal lack of off-link forwarding. The issue is not Router Advertisement configuration; it is the operator's incorrect expectation that two anycast instances should both respond to one request. Check actual routing and destination addressing before changing host gateway advertisement behavior.
C:IPv6 link-local addresses are scoped to an individual link and are not routed normally between networks, but the scenario describes a shared service unicast address advertised from two separate sites. A routed anycast destination is not treated as an on-link `fe80::/10` address solely because multiple interfaces use the same value. If the prefix were link-local, the design would be different and should be investigated separately. That is not the observed single-instance behavior under the described route advertisements.
D:A native VLAN mismatch can divert untagged Ethernet frames into the wrong VLAN and cause connectivity faults, but it does not define how a routed IPv6 anycast address behaves when two service instances advertise it. The client reaches one service and receives a normal reply. No VLAN tag, trunk warning, or reachability failure suggests an 802.1Q issue. The expectation of packet replication belongs to multicast, not anycast; VLAN configuration is irrelevant to that semantic difference.
Question 108
A modified EUI-64 calculation uses Ethernet MAC `00:25:96:12:34:56`, but the derived IID starts `0025` instead of `0225`. Which omitted operation explains the discrepancy?
- The ff:fe bytes should have been inserted at the end of the 64-bit IID instead of between MAC halves.
- The universal/local (U/L) bit of the first MAC octet was not inverted when building the interface identifier.
- The algorithm should convert every hexadecimal digit to decimal before evaluating the U/L bit.
- The MAC must be replaced by an IPv4 subnet mask before an IID can be constructed.
Explanation
Correct Answer
B:Modified EUI-64 inserts FF:FE in the middle of a 48-bit MAC and flips the seventh bit of the first octet. For 00:25:96:12:34:56, the expected IID is 0225:96ff:fe12:3456 rather than 0025:96ff:fe12:3456.
Incorrect Answers
A:The 48-to-64-bit expansion inserts FF:FE between the first and last three MAC octets.
C:The U/L bit is a binary bit in the first octet; decimal reformatting is irrelevant.
D:Modified EUI-64 takes MAC bytes as input and does not use IPv4 mask conversion.
Question 109
A ULA-only IPv6 workstation can reach local peers but not global IPv6 destinations. After adding a global-unicast address and appropriate upstream routing, what test directly demonstrates that the original Internet reachability issue is resolved?
- Confirm a usable global-unicast source, IPv6 default route, and successful IPv6 probe to a permitted public destination using that source.
- Verify that `fd12:...` remains the only source address and claim it is globally routed.
- Check only that the link-local `fe80::` gateway responds on the LAN.
- Check only the IPv6 address spelling, without any routing or successful external packet test.
Explanation
Correct Answer
A:The prefix type explains why the old ULA-only source was not globally reachable, but address classification alone is not a connectivity test. The global source, route to an external next hop and successful forwarded probe establish the repaired end-to-end path.
Incorrect Answers
B:An fc00::/7 ULA alone cannot normally act as a globally reachable IPv6 Internet source.
C:On-link neighbor reachability does not prove a valid global source or end-to-end route to public destinations.
D:A syntactically valid prefix is not enough to prove the global path and return traffic work.
Question 110
A dual-site IPv6 anycast service shares address 2001:db8:99::53. The monitoring team needs evidence that packets are treated as normal unicast toward a route-selected instance, not as multicast delivery to every server. Which observation best demonstrates that forwarding model?
- A Router Advertisement on the client LAN includes a default router lifetime and prefix option.
- The destination is a unicast-format IPv6 address and `show ipv6 route` selects a next hop toward one advertised instance; captures show a request follows that path.
- The local switch reports its interface has a configured IPv6 global unicast address.
- An intrusion-prevention policy logs a dropped TCP connection on the same VLAN.
Explanation
Correct Answer
B:The configured service uses a regular IPv6 unicast destination rather than a multicast group prefix such as `ff00::/8`. A route lookup to 2001:db8:99::53 reveals which next hop the router currently prefers, and a packet observation can corroborate that forwarding decision. Although the same address is present at multiple service sites, one normal unicast request is directed along the selected route; it is not replicated simply because the address is anycast. This verifies the model, whereas the paired diagnostic item corrects the operator's multicast expectation.
Incorrect Answers
A:Router Advertisements help hosts learn on-link prefixes and default routers, but they do not by themselves distinguish unicast anycast service behavior from multicast distribution. A working default route can carry many kinds of destination traffic. The acceptance test must inspect the service destination address and the actual route selected toward a service instance. RA prefix and lifetime fields are useful host-configuration context rather than evidence of which anycast instance receives the tested request.
C:An interface's own IPv6 global address is necessary for many routed deployments but does not show where traffic to this different service address is forwarded. The device might have valid addressing and still lack a route to 2001:db8:99::53 or choose a different site. The evidence should concern the destination lookup and packet path for the actual service. Local addressing state cannot establish whether this flow is unicast or multicast delivery.
D:Intrusion-prevention logs may show blocked traffic and rule decisions, but a drop on a VLAN does not identify the IPv6 destination's address class or prove that an anycast request was replicated. An unrelated blocked TCP session can coexist with a functioning anycast service. The question is about IP forwarding semantics, not security filtering. Inspect the address and routing decision directly and reserve IPS events for a separate policy troubleshooting investigation.
