System Administrator 2026 — Test 40

Correct Answer: B. B. Domain name server
Explanation: Source host queries DNS to determine which version to use when sending a packet to a destination. The DNS contains both, the IPv4 and IPv6 addresses of the modern dual stack host servers.

Correct Answer: D. D. Tunneling
Explanation: In tunneling, The IPv4 routers can form a tunnel in which at the sender’s side, the IPv6 datagram is encapsulated in to IPv4, and at the receiver’s side of the tunnel, the IPv4 packet is stripped and the IPv6 packet is sent to the receiver.

Correct Answer: A. A. Iii-i-ii
Explanation: At the sender’s side, the IPv6 datagram is encapsulated in to IPv4 i.e. An IPv4 header is inserted on top of the IPv6 header, and then the packet is sent through the tunnel.

Correct Answer: B. B. Header translation
Explanation: Header translation is used when the sender wants to use IPv6, but the receiver does not understand IPv6. It is made possible through a Network Address Translation – Protocol Translation enabled device such as a gateway.

Correct Answer: C. C. Mapped address
Explanation: A mapped IPv6 address contains the IPv4 address in its last 32-bits and is preceded by 16 1s and 80 0s. It can be used to translate an IPv6 address to an IPv4 address.

Correct Answer: D. D. The ipv6 flow label is considered
Explanation: In the header translation procedure, first the IPv6 mapped address is changed to an IPv4 address by extracting the rightmost 32bits, then the value of the IPv6 priority field is discarded, and finally the ToS field in the IPv4 header is set to zero. IPv6 flow label is ignored in the procedure.

Correct Answer: B. B. The use of variable length subnet masks is permitted
Explanation: Classful routing means that all hosts in the internetwork use the same mask. Classless routing means that you can use Variable Length Subnet Masks (VLSMs) and can also support discontinuous networking.

Correct Answer: D. D. It describes when a router sets the metric for a downed link to infinity
Explanation: When a network goes down, the distance-vector routing protocol initiates route poisoning by advertising the network with a metric of 16, or unreachable.

Correct Answer: C. C. It has the same timers as ripv1
Explanation: RIPv2 is pretty much just like RIPv1. It has the same administrative distance and timers and is configured just like RIPv1.

Correct Answer: A. A. When a new layer 2-only switch is added to the network
Explanation: Multiple routing protocols are required only when we need to migrate from one routing protocol to another, or when we are using routers from multiple vendors, or when there are host-based routers from multiple vendors. Routing is not a layer-2 function so we don’t require multiple routing protocols when new layer-2 switch is added.