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Question 1. Which of the following best explains why IPv4 address exhaustion occurred? A) IPv4 header contains too many optional fields B) IPv4 uses a 32‑bit address space providing only about 4.3 billion addresses C) IPv4 does not support any form of address translation D) IPv4 packets cannot be fragmented Answer: B Explanation: A 32‑bit address yields roughly 4.3 billion unique addresses, which proved insufficient for the rapid growth of the Internet, leading to exhaustion. Question 2. What is the primary advantage of IPv6’s fixed‑length header over IPv4’s variable‑length header? A) It allows more options to be included directly in the header B) It simplifies router processing and improves forwarding performance C) It enables larger payloads without fragmentation D) It eliminates the need for checksum verification Answer: B Explanation: A fixed‑length header is easier for routers to parse quickly, reducing per‑packet processing time compared with IPv4’s variable‑length header. Question 3. In the IPv6 base header, which field replaces the IPv4 “Time‑to‑Live” (TTL) field? A) Flow Label B) Payload Length C) Hop Limit
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D) Traffic Class Answer: C Explanation: The Hop Limit field decrements by one at each hop and, when it reaches zero, the packet is discarded—functionally equivalent to IPv4’s TTL. Question 4. Which IPv6 extension header is used to carry fragmentation information? A) Hop‑by‑Hop Options Header B) Destination Options Header C) Routing Header D) Fragment Header Answer: D Explanation: The Fragment Header contains the fragment offset, identification, and “more fragments” flag, providing fragmentation support in IPv6. Question 5. Which of the following IPv6 address types is guaranteed to be unique only within a single site and not routable on the global Internet? A) Global Unicast Address (GUA) B) Link‑Local Address (LLA) C) Unique Local Address (ULA) D) Multicast Address Answer: C
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Question 8. How many IPv6 addresses must be configured on an interface to be considered fully IPv6‑enabled according to the RFC? A) One – a link‑local address only B) Two – a link‑local and a global unicast address C) Three – link‑local, global unicast, and multicast address D) Four – link‑local, global unicast, anycast, and multicast Answer: B Explanation: RFC 4291 requires each IPv6 interface to have at least a link‑local address and a globally routable unicast address. Question 9. Which notation correctly compresses the IPv6 address 2001:0db8:0000:0000:0000:ff00:0042:8329? A) 2001:db8::ff00:42: B) 2001:db8:0:0:0:ff00:42: C) 2001:db8::0:ff00:42: D) 2001:db8:0000::ff00:0042: Answer: A Explanation: Zero compression replaces the longest consecutive run of 16‑bit zero fields with “::”, yielding 2001:db8::ff00:42:8329. Question 10. According to RFC 5952, which of the following is the preferred representation of an IPv address? A) Use uppercase hexadecimal digits
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B) Omit leading zeros in each 16‑bit field C) Use the longest possible sequence of “::” even if multiple exist D) Separate fields with hyphens Answer: B Explanation: RFC 5952 recommends suppressing leading zeros in each field while keeping the address in lowercase. Question 11. When generating an Interface Identifier (IID) using the EUI‑64 method from a 48‑bit MAC address, which bits are modified? A) The universal/local (U/L) bit is flipped from 0 to 1 B) The universal/local (U/L) bit is flipped from 1 to 0 C) The group (G) bit is set to 1 D) No bits are changed; the MAC is simply padded Answer: A Explanation: The U/L bit (the seventh bit of the first octet) is inverted to indicate that the address is globally unique, then the MAC is split and “FFFE” inserted. Question 12. Which IPv6 addressing feature provides temporary addresses to improve user privacy? A) Stateless Address Autoconfiguration (SLAAC) B) DHCPv6 prefix delegation C) Privacy Extensions (RFC 4941) D) Unique Local Addresses (ULA)
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Question 15. An ISP allocates a /48 block to a customer. How many /64 subnets can the customer obtain from this allocation? A) 16 B) 256 C) 4, D) 65, Answer: D Explanation: Each increment of 16 bits (from /48 to /64) yields 2¹⁶ = 65,536 possible /64 subnets. Question 16. Which IPv6 address format is used for the solicited‑node multicast address of the unicast address 2001:db8::1? A) ff02::1:ff00: B) ff02::1:ff00: C) ff02::1:ff00: D) ff02::1:ff00: Answer: A Explanation: The solicited‑node address is ff02::1:ff + the low‑order 24 bits of the unicast address (0x000001), resulting in ff02::1:ff00:1. Question 17. Which ICMPv6 message type is used by a router to indicate that a packet is too large for the next hop’s MTU? A) Destination Unreachable (1)
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B) Packet Too Big (2) C) Time Exceeded (3) D) Parameter Problem (4) Answer: B Explanation: ICMPv6 type 2 (“Packet Too Big”) informs the sender of the maximum transmission unit of the next hop. Question 18. In Neighbor Discovery, which flag in the Router Advertisement indicates that hosts should use DHCPv6 for address configuration? A) M (Managed) flag B) O (Other) flag C) L (Link‑layer address) flag D) A (Autonomous) flag Answer: A Explanation: The Managed (M) flag tells hosts to obtain addresses via stateful DHCPv6. Question 19. Which Router Advertisement flag tells hosts to use the advertised prefix for autonomous address configuration (SLAAC)? A) M (Managed) flag B) O (Other) flag C) L (Link‑layer address) flag D) A (Autonomous) flag
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A) To inform a host of a better next‑hop for a specific destination on the same link B) To request a new Router Advertisement from a router C) To announce a change in the link‑local prefix D) To indicate that a packet was dropped due to ACL violation Answer: A Explanation: ICMPv6 Redirect (type 137) tells a host that a more optimal next‑hop exists for a destination reachable on the same link. Question 23. Which of the following best describes the mapping of a solicited‑node multicast address to an Ethernet MAC address? A) 33:33:ff:XX:XX:XX where XX:XX:XX are the low 24 bits of the IPv6 address B) 01:00:5e:XX:XX:XX where XX:XX:XX are the low 23 bits of the IPv6 address C) 00:00:5e:ff:XX:XX where XX:XX are the low 16 bits of the IPv6 address D) 33:33:00:XX:XX:XX where XX:XX:XX are the low 24 bits of the IPv6 address Answer: A Explanation: IPv6 multicast addresses are mapped to Ethernet MACs using the prefix 33:33:ff followed by the low 24 bits of the IPv6 address. Question 24. Which static routing option in IPv6 allows a route to be used only when a higher‑priority route fails? A) Recursive static route B) Floating static route with a higher administrative distance C) Directly connected static route
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D) Fully specified static route Answer: B Explanation: A floating static route is configured with a higher administrative distance, making it a backup that becomes active only if the primary route goes down. Question 25. In OSPFv3, which LSA type carries IPv6 prefix information for router‑links? A) Type 1 – Router LSA B) Type 2 – Network LSA C) Type 3 – Summary LSA D) Type 5 – External LSA Answer: A Explanation: OSPFv3 Type 1 Router LSAs contain link‑local addresses and IPv6 prefixes for the router’s interfaces. Question 26. Which OSPFv3 feature differentiates it from OSPFv2 regarding the handling of link‑state advertisements? A) OSPFv3 advertises IPv6 addresses in separate LSAs per link B) OSPFv3 uses the same LSA types as OSPFv2 but includes an IPv6 flag C) OSPFv3 does not support area hierarchies D) OSPFv3 runs over TCP instead of IP Answer: A
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Question 29. In the DUAL algorithm used by EIGRP for IPv6, which term describes a backup route that satisfies the feasibility condition? A) Successor B) Feasible Successor C) Loop‑Free Alternate D) Backup Neighbor Answer: B Explanation: A Feasible Successor is a backup route that meets the feasibility condition (its reported distance is less than the successor’s feasible distance). Question 30. In MP‑BGP, which AFI value indicates the address family is IPv6? A) 1 B) 2 C) 4 D) 6 Answer: B Explanation: AFI 2 is defined for IPv6 in the MP‑BGP extensions, while AFI 1 denotes IPv4. Question 31. Which SAFI value is used when MP‑BGP carries IPv6 unicast routes? A) 1 (Unicast) B) 2 (Multicast) C) 4 (MPLS‑VPN)
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D) 128 (Labeled Unicast) Answer: A Explanation: SAFI 1 corresponds to the unicast address family; combined with AFI 2, it carries IPv unicast routes. Question 32. When establishing an IPv6 BGP session over an existing IPv4 TCP connection, which term describes this technique? A) Dual‑stack BGP B) MP‑BGP over IPv4 transport (BGP‑MP‑IPv4) C) BGP‑4 over IPv D) BGP‑VPN Answer: B Explanation: MP‑BGP can run over an IPv4 TCP transport, allowing IPv6 routes to be exchanged without requiring native IPv6 connectivity. Question 33. In a dual‑stack host, which DNS record type is queried to obtain an IPv6 address? A) A B) AAAA C) CNAME D) PTR Answer: B Explanation: The AAAA DNS record holds the IPv6 address associated with a hostname.
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C) The IPv4 address of the nearest DNS server D) The IPv4 address of the default gateway Answer: B Explanation: 6to4 uses the host’s public IPv4 address to create a /48 IPv6 prefix in the format 2002:V4ADDR::/48. Question 37. Which IPv6 transition technology uses a virtual IPv6 address derived from a host’s IPv address and a well‑known IPv6 prefix 2001:0::/32? A) ISATAP B) Teredo C) 6to D) GRE Answer: B Explanation: Teredo encapsulates IPv6 packets inside UDP/IPv4 and assigns a /64 prefix of 2001:0::/32, embedding the client’s public IPv4 address and port. Question 38. In NAT64, which component translates IPv6 client‑side addresses to IPv4 server‑side addresses? A) DNS64 server B) Stateless NAT64 gateway C) Stateful NAT64 translator D) IPv6‑only router
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Answer: C Explanation: Stateful NAT64 maintains mapping tables to translate IPv6 source addresses to IPv addresses and vice‑versa, enabling communication with IPv4‑only servers. Question 39. Which DNS64 function synthesizes AAAA records for domains that have only A records? A) Forwarding queries to an upstream IPv6‑only DNS server B) Appending the NAT64 prefix to the IPv4 address to form a fake AAAA record C) Returning a DNS REFUSED response D) Performing DNSSEC validation Answer: B Explanation: DNS64 constructs a synthetic AAAA record by prefixing the IPv4 address with the configured NAT64 prefix, enabling IPv6 clients to reach IPv4‑only hosts. Question 40. Which statement accurately distinguishes stateful from stateless NAT64? A) Stateful NAT64 assigns a fixed IPv6 address to each IPv4 host, while stateless does not keep mappings. B) Stateless NAT64 uses a one‑to‑one mapping algorithm without per‑session state, whereas stateful maintains dynamic translation tables. C) Stateful NAT64 works only for UDP traffic, while stateless works only for TCP. D) Stateless NAT64 requires DNS64, while stateful does not. Answer: B Explanation: Stateless NAT64 translates based on a deterministic algorithm (e.g., embedding IPv address in IPv6), needing no per‑session state; stateful NAT64 tracks each session in a translation table.
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B) Destination IPv6 address C) Traffic Class field D) Flow Label field Answer: D Explanation: IPv6 ACLs can be configured to match the 20‑bit Flow Label, allowing selective filtering of flows with specific labels. Question 44. By default, which IPv6 ICMP types are implicitly permitted by most router ACLs? A) Echo Request and Echo Reply only B) All ICMPv6 types are denied unless explicitly permitted C) Destination Unreachable, Packet Too Big, Time Exceeded, and Parameter Problem D) Router Solicitation, Router Advertisement, Neighbor Solicitation, Neighbor Advertisement Answer: D Explanation: IPv6 routers must allow essential NDP and RA traffic for proper neighbor discovery; these messages are implicitly permitted in many default ACL configurations. Question 45. Which IPsec mode provides end‑to‑end security between two IPv6 hosts? A) Tunnel mode B) Transport mode C) Secure Tunnel mode D) Authentication Header (AH) only
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Answer: B Explanation: Transport mode encrypts only the payload of the IPv6 packet, providing direct host‑to‑host confidentiality and integrity. Question 46. In IPv6 IPsec tunnel mode, which part of the original packet is encrypted? A) Only the payload, leaving the original IPv6 header intact B) The entire original packet, including its IPv6 header, which becomes the payload of the new outer IPv6 header C) Only the Transport Layer (TCP/UDP) headers D) Only the ICMPv6 messages Answer: B Explanation: Tunnel mode encapsulates the entire original IPv6 packet (header + payload) within a new IPv6 header, encrypting the inner packet entirely. Question 47. Which version of SNMP can operate natively over IPv6 without additional extensions? A) SNMPv B) SNMPv2c C) SNMPv D) All of the above Answer: D Explanation: All SNMP versions (v1, v2c, v3) support IPv6 transport because they rely on UDP/TCP, which are IPv6‑aware.
