CCNA 640-802: IPv6

1. As a CCNA candidate, you must have a firm understanding of the IPv6 address structure. Refer to IPv6 address, could you tell me how many bits are included in each filed?

A – 24
B – 4
C – 3
D – 16

Answer: D

The format of a IPv6 address is X:X:X:X:X:X:X:X where X is a 16-bit hexadecimal field. For example: 110A:0192:190F:0000:0000:082C:875A:132c

2. In practical IPv6 application, a technology encapsulates IPv6 packets inside IPv4 packets, this technology is called what?

A – tunneling
B – hashing
C – routing

Answer: A

3. Internet Protocol version 6 (IPv6) is the next-generation Internet Protocol version designated as the successor to IPv4 because IPv4 address space is being exhausted. Which one of the following descriptions about IPv6 is correct?

A – Addresses are not hierarchical and are assigned at random.
B – Broadcasts have been eliminated and replaced with multicasts.
C – There are 2.7 billion available addresses.
D – An interface can only be configured with one IPv6 address.

Answer: B

4. Which two of these statements are true of IPv6 address representation? (Choose two)

A – The first 64 bits represent the dynamically created interface ID.
B – A single interface may be assigned multiple IPV6 addresses of any type.
C – Every IPV6 interface contains at least one loopback address.
D – Leading zeros in an IPV6 16 bit hexadecimal field are mandatory.

Answer: B C

Leading zeros in IPv6 are optional do that 05C7 equals 5C7 and 0000 equals 0 -> D is not corect.

5. Which three of the following are IPv6 transition mechanisms? (Choose three)

A – 6to4 tunneling
B – GRE tunneling
C – ISATAP tunneling
D – Teredo tunneling
E – VPN tunneling
F – PPP tunneling

Answer: A C D

Below is a summary of IPv6 transition technologies:

6 to 4 tunneling: This mechanism allows IPv6 sites to communicate with each other over the IPv4 network without explicit tunnel setup. The main advantage of this technology is that it requires no end-node reconfiguration and minimal router configuration but it is not intended as a permanent solution.

ISATAP tunneling (Intra-Site Automatic Tunnel Addressing Protocol): is a mechanism for transmitting IPv6 packets over IPv4 network. The word “automatic” means that once an ISATAP server/router has been set up, only the clients must be configured to connect to it.

Teredo tunneling: This mechanism tunnels IPv6 datagrams within IPv4 UDP datagrams, allowing private IPv4 address and IPv4 NAT traversal to be used.

In fact, GRE tunneling is also a IPv6 transition mechanism but is not mentioned in CCNA so we shouldn’t choose it (there are 4 types of IPv6 transition mechanisms mentioned in CCNA; they are: manual, 6-to-4, Teredo and ISATAP).

6. Which two descriptions are correct about characteristics of IPv6 unicast addressing? (Choose two)

A – Global addresses start with 2000::/3.
B – Link-local addresses start with FF00::/10.
C – Link-local addresses start with FE00:/12.
D – There is only one loopback address and it is ::1.

Answer: A D

Below is the list of common kinds of IPv6 addresses:

Loopback address ::1
Link-local address FE80::/10
Site-local address FEC0::/10
Global address 2000::/3
Multicast address FF00::/8

7. Select the valid IPv6 addresses. (Choose all apply)

A – ::192:168:0:1
B – 2002:c0a8:101::42
C – 2003:dead:beef:4dad:23:46:bb:101
D – ::
E – 2000::
F – 2001:3452:4952:2837::

Answer: A B C D F

Answers A B C are correct because A and B are the short form of 0:0:0:0:192:168:0:1 and 2002:c0a8:0101:0:0:0:0:0042 while C are normal IPv6 address.

Answer D is correct because “::” is named the “unspecified” address and is typically used in the source field of a datagram that is sent by a device that seeks to have its IP address configured.

Answer E is not correct because a global-unicast IPv6 address is started with binary 001, denoted as 2000::/3 in IPv6 and it also known as an aggregatable global unicast address.The 2000:: (in particular, 2000::/3) is just a prefix and is not a valid IPv6 address.

The entire global-unicast IPv6 address range is from 2000::/128 to 3FFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF/128, resulting in a total usable space of over 42,535,295,865,117,307,932,921,825,928,971,000,000 addresses, which is only 1/8th of the entire IPv6 address space!

8. What is the Multicast for all-router muticast access?

A – FF02::4
B – FF02::3
C – FF02::2
D – FF02::1

Answer: C


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