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IPv6 Questions 3

May 2nd, 2017 Go to comments

Note: If you are not sure about IPv6, please read our IPv6 tutorial.

Question 1

Explanation

A IPv6 Unique Local Address is an IPv6 address in the block FC00::/7, which means that IPv6 Unique Local addresses begin with 7 bits with exact binary pattern as 1111 110 -> Answer B is correct.

Note: IPv6 Unique Local Address is the approximate IPv6 counterpart of the IPv4 private address. It is not routable on the global Internet.

Question 2

Explanation

Neighbor Discovery Protocol is an umbrella that defines these mechanisms:
+ Subsitute of ARP – Since ARP has been removed in IPv6, IPv6 follows a newer way to find the link-layer addresses of nodes on the local link. This new mechanism uses a mix of ICMPv6 messages and multicast addresses

Reference: https://supportforums.cisco.com/document/77521/ipv6-neighbor-discovery-protocol-ndp

Question 3

Question 4

Explanation

Only three connection types are commonly known and used in Internet Protocol version four (IPv4) networks: unicast, multicast and broadcast. A fourth connection type, Anycast, was unknown until IPv6 made it a standard connection type. Anycast is not standardized in IPv4 but can be emulated. IPv4 Anycast addressing is a good solution to provide localization for services and servers in order to obtain robustness, redundancy and resiliency.

The basic idea of Anycast is very simple: multiple servers, which share the same IP address, host the same service. The routing infrastructure sends IP packets to the nearest server (according to the metric of the routing protocol used). The major benefits of employing Anycast in IPv4 are improved latency times, server load balancing, and improved security.

Reference: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.116.6367&rep=rep1&type=pdf

Question 6

Question 7

Explanation

Floating static routes are static routes that have an administrative distance greater than the administrative distance (AD) of another static route or dynamic routes. By default a static route has an AD of 1 then floating static route must have the AD greater than 1 -> Answer A is correct as it has the AD of 201.

Question 8

Explanation

Each ISP receives a /32 and provides a /48 for each site-> every ISP can provide 2(48-32) = 65,536 site addresses (note: each network organized by a single entity is often called a site).

ipv6_Address_Allocation_Policy.jpg

Each site provides /64 for each LAN -> each site can provide 2(64-48) = 65,536 LAN addresses for use in their private networks.
So each LAN can provide 264 interface addresses for hosts.

-> Global routing information is identified within the first 64-bit prefix.

Now let’s see an example of IPv6 prefix: 2001:0A3C:5437:ABCD::/64:

IPv6_prefix_length_example.jpg

In this example, the RIR has been assigned a 12-bit prefix. The ISP has been assigned a 32-bit prefix and the site is assigned a 48-bit site ID. The next 16-bit is the subnet field and it can allow 216, or 65536 subnets. This number is redundant for largest corporations on the world!

The 64-bit left (which is not shown the above example) is the Interface ID or host part and it is much more bigger: 64 bits or 264 hosts per subnet! For example, from the prefix 2001:0A3C:5437:ABCD::/64 an administrator can assign an IPv6 address 2001:0A3C:5437:ABCD:218:34EF:AD34:98D to a host.

Question 9

Explanation

Link-local addresses refer only to a particular physical link and are used for addressing on a single link for purposes such as automatic address configuration and neighbor discovery protocol. Link-local addresses can be used to reach the neighboring nodes attached to the same link. The nodes do not need a globally unique address to communicate. Routers will not forward datagram using link-local addresses. All IPv6 enabled interfaces have a link-local unicast address.

A link-local address is an IPv6 unicast address that can be automatically configured on any interface using the link-local prefix FE80::/10 (1111 1110 10) and the interface identifier in the modified EUI-64 format. Link-local addresses are not necessarily bound to the MAC address (configured in a EUI-64 format). Link-local addresses can also be manually configured in the FE80::/10 format using the “ipv6 address link-local” command.

Reference: http://www.cisco.com/c/en/us/support/docs/ip/ip-version-6-ipv6/113328-ipv6-lla.html

In summary, if you do not configure a link-local on an IPv6 enabled interface, it will automatically use the FE80::/10 and the interface identifier in the modified EUI-64 format to form a link-local address.

Question 10

Question 11

Explanation

Let’s see an example of IPv6 prefix: 2001:0A3C:5437:ABCD::/64:

IPv6_prefix_length_example.jpg

In this example, the RIR has been assigned a 12-bit prefix. The ISP has been assigned a 32-bit prefix and the site is assigned a 48-bit site ID. The next 16-bit is the subnet field and it can allow 216, or 65536 subnets. This number is redundant for largest corporations on the world!

The 64-bit left (which is not shown the above example) is the Interface ID or host part and it is much more bigger: 64 bits or 264 hosts per subnet!

Therefore in this question 4079 is the subnet ID. The FD14 prefix belongs to FC00::/7 which is an IPv6 Unique Local Address (The address block fc00::/7 is divided into two /8 groups which are FC00::/8 & FD00::/8)

Question 12

Explanation

Below lists some reserved and well-known IPv6 multicast address in the reserved multicast address range:

FF01::1 All IPv6 nodes within the node-local scope
FF01::2 All IPv6 routers within the node-local scope
FF02::1 All IPv6 nodes within the link-local scope
FF02::2 All IPv6 routers within the link-local scope
FF02::5 All OSPFv3 routers within the link-local scope
FF02::6 All OSPFv3 designated routers within the link-local scope
FF02::9 All RIPng routers within the link-local scope
FF02::A All EIGRP routers within the link-local scope
FF02::D All PIM routers within the link-local scope
FF02::1:2 All DHCPv6 agents (servers and relays) within the link-local scope
FF05::2 All IPv6 routers within the site-local scope
FF02::1:FF00:0/104 IPv6 solicited-node multicast address within the link-local scope

Question 13

Explanation

Any IPv6 address that begins with the 2002::/16 prefix is known as a 6to4 address. A 6to4 gateway adds its IPv4 address to this 2002::/16, creating a unique /48 prefix (because an IPv4 consists of 32 bits).

For example: In the IPv6 address 2002:ab10:beef::/48, “ab10:beef” is equivalent to 171.16.190.239 (convert “ab” in hexadecimal to “171” in decimal; “10” in hexadecimal to “16” in decimal…). Therefore the corresponding IPv4 address can be globally routed.

Question 14

Explanation

On inter-router point-to-point links, it is useful, for security and other reasons, to use 127-bit IPv6 prefixes. Such a practice parallels the use of 31-bit prefixes in IPv4.

Reference: https://tools.ietf.org/html/rfc6164

Question 15

Comments (11) Comments
  1. gigi
    June 21st, 2017

    please provide the link to 9tut Questions pdf.
    thank you!

  2. Michel
    June 30th, 2017

    Found this VCE with the CCNA questions, can anyone confirm if this are valid https://drive.google.com/open?id=0B5mAFqgydmCza1ViTmFlNkQwYzg

  3. Advice
    July 25th, 2017

    Question 1 answer isn’t written correctly. It show “1111 1100” instead of “1111 1110” like in the explanation.

  4. Advice
    July 25th, 2017

    Wait nvm I figured it out.

  5. nickaro
    August 15th, 2017

    As Advice says, in Q.1 there’s something wrong…

  6. nickaro
    August 15th, 2017

    Q.4 isn’t commented. What is seemed to be answer 4 comment, it is actually answer 5’s…

  7. Anonymous
    August 17th, 2017

    Hello am not able to see questions. yet i was seeing them yesterday when I paid membership.

  8. charles
    August 17th, 2017

    Hello am not able to see questions. yet i was seeing them yesterday when I paid membership

  9. 9tut
    August 17th, 2017

    @charles: If your problem still exists, please send an email to support@9tut.com so that we can help you.

  10. AN
    September 20th, 2017

    Q8 Must be C, F according to:
    https://tools.ietf.org/html/rfc4193
    (Section 3.2 Global ID)

  11. AN
    September 20th, 2017

    3.1. Format

    The Local IPv6 addresses are created using a pseudo-randomly
    allocated global ID. They have the following format:

    | 7 bits |1| 40 bits | 16 bits | 64 bits |
    +——–+-+————+———–+—————————-+
    | Prefix |L| Global ID | Subnet ID | Interface ID |
    +——–+-+————+———–+—————————-+

    Where:

    Prefix FC00::/7 prefix to identify Local IPv6 unicast
    addresses.

    L Set to 1 if the prefix is locally assigned.
    Set to 0 may be defined in the future. See
    Section 3.2 for additional information.

    Global ID 40-bit global identifier used to create a
    globally unique prefix. See Section 3.2 for
    additional information.

    Subnet ID 16-bit Subnet ID is an identifier of a subnet
    within the site.

    Interface ID 64-bit Interface ID as defined in [ADDARCH].

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