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2013 Latest Cisco 350-001 Exam Section 5: IPv6 (8 Questions)

QUESTION NO: 1
What best describes the IPv6 Solicited-node Multicast address?

A. For each unicast and anycast addresses configured on an interface of the node or a router, a corresponding solicited-node multicast addresses is automatically enabled.
B. The solicited-node multicast address is scoped at the local link.
C.
Since ARP is not used the in IPv6, the solicited-node multicast addresses is used by nodes

and router to learn the link layer address of the neighbor nodes and routers on the same
local link.
D. Duplicate Address Detection (DAD) is used to verify if the IPv6 address is already in used on it’s local link, before it configure it’s own IPv6 address with stateless auto-configuration, Solicited-node multicast addresses probe the local link to make sure.
E. All of the above
F. None of the above
Answer: E
Explanation:
In IP version 6, the solicited-node multicast address facilitates efficient querying of network nodes during address resolution. IPv6 uses the Neighbor Solicitation message to perform address resolution. In IPv4, the ARP Request frame is sent to the MAC-level broadcast, disturbing all nodes on the network segment regardless of whether a node is running IPv4. For IPv6, instead of using ARP requests and disturbing all IPv6 nodes on the local link by using the local-link scope all-nodes address, the solicited-node multicast address is used as the Neighbor Solicitation message destination. The solicited-node multicast address consists of the prefix FF02::1:FF00:0/104 and the last 24-bits of the IPv6 address that is being resolved. The following steps show an example of how the solicited-node address is handled for the node with the link-local IPv6 address of FE80::2AA:FF:FE28:9C5A, and the corresponding solicited-node address is FF02::1:FF28:9C5A:
1.
To resolve the FE80::2AA:FF:FE28:9C5A address to its link layer address, a node sends a Neighbor Solicitation message to the solicited-node address of FF02::1:FF28:9C5A.
2.
The node using the address of FE80::2AA:FF:FE28:9C5A is listening for multicast traffic at the solicited-node address FF02::1:FF28:9C5A. For interfaces that correspond to a physical network adapter, it has registered the corresponding multicast address with the network adapter.
As shown in this example, by using the solicited-node multicast address, address resolution that commonly occurs on a link can occur without disturbing all network nodes. In fact, very few nodes are disturbed during address resolution. Because of the relationship between the network interface MAC address, the IPv6 interface ID, and the solicited-node address, in practice, the solicited-node address acts as a pseudo-unicast address for efficient address resolution.
Reference:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcetcpip/html/cmconmulticastipv6addres

QUESTION NO: 2
What is a main difference between the IPv6 and IPv4 multicast?

A. IPv6 has significantly more address space (128 bits), so overlapping addresses are less likely.
B. Multicast Listener Discovery (MLD) replaces IGMP in IPv6 multicasts.
C. MSDP and dense mode multicast is not part of IPv6 multicast.
D. The first 8 bits of Ipv6 Multicast address are always FF (1111 1111).
E. All of the above
Answer: E
Explanation:
A multicast address identifies multiple interfaces, and is used for one-to-many communication. With the appropriate multicast routing topology, packets addressed to a multicast address are delivered to all interfaces that are identified by the address. IPv6 multicast addresses have the Format Prefix of 1111 1111. An IPv6 address is simple to classify as multicast because it always begins with FF. Multicast addresses cannot be used as source addresses. Multicast addresses include additional structure to identify their flags, scope, and multicast group, as shown in the following illustration.
MLD is used to exchange membership status information between IPv6 routers that support multicasting and members of multicast groups on a network segment. Membership in a multicast group is reported by individual member hosts, and membership status is periodically polled by multicast routers. MLD is defined in RFC 2710, “Multicast Listener Discovery (MLD) for IPv6.” IGMP is not used in IPv6.

QUESTION NO: 3
What best describes the functionality of the Multicast Listener Discovery (MLD)?

A. IPv6 routers use MLD to discover multicast listeners on directly attached links.
B. For each Unicast and Anycast addresses configured on an interface of the node or a

router, a corresponding entry is automatically enabled.
C. The MLD addresses is scoped to the local link.
D. Since the ARP is not used in the IPv6, the MLD is used by nodes and routers to learn the link layer address of the neighbor nodes and routers on the same local link.
E. MLD is used to verify if the IPv6 address is already in use on it’s local link, before it configure it’s own IPv6 address with stateless auto-configuration.
Answer: A
Explanation:
The purpose of Multicast Listener Discovery (MLD) is to enable each IPv6 router to discover the presence of multicast listeners (that is, nodes wishing to receive multicast packets) on its directly attached links, and to discover specifically which multicast addresses are of interest to those neighboring nodes. This information is then provided to whichever multicast routing protocol is being used by the router, in order to ensure that multicast packets are delivered to all links where there are interested receivers. MLD is an asymmetric protocol, specifying different behaviors for multicast listeners and for routers. For those multicast addresses to which a router itself is listening, the router performs both parts of the protocol, including responding to its own messages. If a router has more than one interface to the same link, it need perform the router part of MLD over only one of those interfaces. Listeners, on the other hand, must perform the listener part of MLD on all interfaces from which an application or upper-layer protocol has requested reception of multicast packets.

QUESTION NO: 4 The TestKing network is migrating from IPv4 to IPv6. What IPv6 header field has a similar function as the “Type of Service” field in an IPv4 header?
A. Flow Label
B. Version
C. Next Header
D. Traffic Class
E. None of above
Answer: D
Explanation:
The IPV6 header is shown below:
Packet Fields

Version The version field exists for the same purpose as in IPv4, namely to differentiate between different versions of the protocol. Obviously it carries the value of “6” for all IPv6 packets. Traffic Class
This is similar to the Type of Service (ToS) bits in IPv4, except that it tries to describe the type of traffic rather than the type of service.
Flow Label This is used to label a “flow” of packets. On problem with a packet switching network is that there’s no good way to tell if a bunch of separate packets are related to each other. Payload Length This is the length of the packet not including the IPv6 header. It replaces the Total Length field in IPv4. Unlike IPv4, IPv6 headers are of a fixed length, and there’s no point in adding a constant to the length field. Next Header This is like the Protocol field from IPv4 – it identifies the higher level protocol. However, unlike IPv4, this is not always a transport layer protocol like TCP or UDP. It takes on special values which are used to implement the IPv6 extension and option mechanisms. Hop Limit This is like the TTL (Time To Live) field from IPv4 – it’s used to minimize the resources that a packet consumes in the event of a routing loop. Its name has been changed to reflect the actual usage of the field. Namely, it is decremented every hop, rather than every second as was originally intended.
Source/Destination Address
These have the same purpose in IPv4, but have been expanded to 128 bits.

Reference: http://www.mit.edu/~elliot/internet/1998/ipv6-notes.html

QUESTION NO: 5
When comparing the header fields in IP version 4 and IP version 6, what lPv6 header field has a similar function as the IPv4 header field “Type of Service”?
A. Flow Label
B. Version
C. Next Header
D. None of above
E. All of the above
Answer: D
Explanation:
This question is fundamentally the same as number 4 above, except the correct answer
“Traffic Class” has been omitted, making choice D correct.
In an IPv6 header, the “Traffic Class” field similar in function to the “ToS” field in IPv4.
The IPV6 header is shown below:

Packet Fields
Version The version field exists for the same purpose as in IPv4, namely to differentiate between different versions of the protocol. Obviously it carries the value of “6” for all IPv6 packets. Traffic Class
This is similar to the Type of Service (ToS) bits in IPv4, except that it tries to describe the type of traffic rather than the type of service.
Flow Label This is used to label a “flow” of packets. On problem with a packet switching network is that there’s no good way to tell if a bunch of separate packets are related to each other. Payload Length This is the length of the packet not including the IPv6 header. It replaces the Total Length field in IPv4. Unlike IPv4, IPv6 headers are of a fixed length, and there’s no point in adding a constant to the length field. Next Header This is like the Protocol field from IPv4 – it identifies the higher level protocol. However, unlike IPv4, this is not always a transport layer protocol like TCP or UDP. It takes on special values which are used to implement the IPv6 extension and option mechanisms. Hop Limit This is like the TTL (Time To Live) field from IPv4 – it’s used to minimize the resources that a packet consumes in the event of a routing loop. Its name has been changed to reflect the actual usage of the field. Namely, it is decremented every hop, rather than every second as was originally intended. Reference: http://www.mit.edu/~elliot/internet/1998/ipv6-notes.html

QUESTION NO: 6 Which of the following are legal representations of the IPv6 prefix 12AB00000000CD3? (Choose Two)
A. 12AB:0000:0000:CD30:0000:0000:0000:0000/60
B. 12AB:0:0:CD3/60
C. 12AB:: CD3/60
D. 12AB:0:0:CD30::/60
E. 12AB::CD3::/60
Answer: A, D
Explanation:
IPv6 Address Compaction:
In IPv6, the leading zeroes in a 16-bit segment can be compacted.
Example:
fe80:0210:1100:0006:0030:a4ff:000c:0097 becomes fe80:210:1100:6:30:a4ff:c:97
All zeroes in one or more contiguous 16-bit segments can also be represented with a
double colon(::).
Example:
ff02:0000:0000:0000:0000:0000:0000:0001Becomes ff02::1.
However, double colons can only be used once in any one address.
Example:
2001:0000:0000:0013:0000:0000:0b0c:3701
Can be:
2001::13:0:0:b0c:3701 or 2001:0:0:13::b0c:3701, but not 2001::13::b0c:3701
For IPv6 Prefix Representation, CIDR-like notations are used to specify the address
prefix length. Examples of this include:
3ffe:0:0:2300:ce21:233:fea0:bc94/60 and 201:468:1102:1::1/64
Finally, an IPv6 Prefix Compaction example is:
2002:0000:0000:18d0:0000:0000:0000:0000/60
Can be represented as:
2002::18d0:0:0:0:0/60
2002:0:0:18d0::/60
In the example shown in this question, 12AB00000000CD3 can be represented either as:
12AB:0000:0000:CD30:0000:0000:0000:0000/60 or 12AB:0:0:CD30::/60

QUESTION NO: 7 IPv6 is being implemented in the TestKing network. Which of the following is a valid IPv6 Address Type? (Choose Three)
A. Broadcast
B. Multicast
C. Anycast
D. Unicast
Answer: B, C, D
Explanation:
With IPv6 the IETF sought to carve the new address space into functional categories,
each of which would enable more-efficient routing through a more-sophisticated
hierarchy. These functional categories are known as anycast, unicast, and multicast.
Noticeably absent was the broadcast address type. IPv6 doesn’t use broadcast addresses,
but it satisfies that function through the multicast address type.
IPv6 defines three address types:

Unicast:
Identifies an interface of an individual node.
Multicast:
Identifies a group of interfaces, usually on different nodes. Packets that are sent to the multicast address go to all members of the multicast group.
Anycast:
Identifies a group of interfaces, usually on different nodes. Packets that are sent to the anycast address go to the anycast group member node that is physically closest to the sender.

QUESTION NO: 8
Router TK1 needs to be configured with RIP to support IPv6. Which of the
following are the minimum required tasks to configure IPv6 RIP on a Cisco router?
(Choose Two)

A. Customizing IPv6 RIP
B. Configuring Tags for RIP routes
C. Enable IPv6 RIP on the interface
D. Configuring IPv6 Multicast routing
E. Enable IPv6 on the router
Answer: C, E
Explanation:
Before configuring the router to run IPv6 RIP, two things must be done. First, globally enable IPv6 using the “ipv6 unicast-routing” global configuration command. Secondly, enable IPv6 on any interfaces on which IPv6 RIP is to be enabled. These are the required minimum configuration prerequisites.
Incorrect Answers:
A, B, D: These choices describe optional IPv6 RIP configurations. A list of optional components for configuring RIP for IPv6 is shown below:
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00801d6601.ht
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