1.8 IPv6 Addressing

Question 1

Define:

IPv6 addressing?

Answer 1

A system for assigning 128-bit IP addresses.

IPv6 was introduced to overcome IPv4 address exhaustion and provide more address space.

Question 2

Describe the structure of an IPv6 address.

Answer 2

It has eight groups of four hexadecimal digits.

It’s 128 bits long, and each group is separated by colons, representing the address in a compressed format.

Question 3

Why is IPv6 addressing necessary?

Answer 3

Due to IPv4 address exhaustion.

IPv6 offers a significantly larger address space, accommodating the growing number of internet-connected devices.

Question 4

What are the benefits of IPv6 over IPv4.

Answer 4

• Larger address space
• Improved security
• Simpler header structure
• Better routing efficiency

Larger address space: Allows more unique IP addresses for devices.

Improved security: Supports built-in IPsec for secure communication.

Simpler header structure: Streamlines packet processing.

Better routing efficiency: Reduces routing table size and improves speed.

Question 5

Why is IPv6 more secure than IPv4?

Answer 5

It mandates features like IPsec for encryption and authentication.

IPsec is optional in IPv4 but a required component of IPv6 for enhanced security.

Question 6

True or False:

IPv6 addresses use dotted-decimal notation.

Answer 6

False

IPv6 addresses use hexadecimal notation, not the dotted-decimal format of IPv4.

Question 7

What is the range of an IPv6 link-local address?

Answer 7

fe80::/10

IPv6 link-local addresses fall within the fe80::/10 prefix, specifically ranging from fe80:: to febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff.

Question 8

Why do IPv6 addresses use hexadecimal instead of decimal?

Answer 8

It is more efficient for representing binary data.

Each hex digit represents four bits, making the address shorter and easier to read.

Question 9

Describe how an IPv6 address is assigned to a device.

Answer 9

It can be assigned manually, via DHCPv6, or SLAAC.

Stateless Address Autoconfiguration (SLAAC) allows devices to configure their own address based on router information, while DHCPv6 requires a server to assign the address automatically.

Question 10

What does the term autoconfiguration mean in IPv6?

Answer 10

The automatic assignment of an IPv6 address to a device.

This process includes the creation of a link-local address and can use Stateless Address Autoconfiguration (SLAAC) or DHCPv6.

Question 11

List the steps involved in configuring IPv6 addressing on a router.

Answer 11

1. Enable IPv6 routing.
2. Assign an IPv6 address to the interface.
3. Activate the interface.
4. Verify the configuration with show ipv6 interface.

These steps allow the router to handle IPv6 traffic and route packets appropriately.

Question 12

What is the IPv6 equivalent of an IPv4 subnet mask?

Answer 12

The prefix length.

The prefix length, written as /n, defines the size of the network in IPv6 addresses (e.g., /64).

Question 13

True or False:

IPv6 supports private addresses similar to IPv4’s private address space.

Answer 13

True

IPv6 has Unique Local Addresses (ULA), similar to IPv4’s private address range, used in internal networks.

Question 14

Fill in the blank:

The IPv6 address block fd00::/8 in IPv6 is reserved for ______ ______ addresses.

Answer 14

Unique Local

ULAs are used for private communication within an organization, similar to IPv4 private addresses.

Question 15

What is the significance of the link-local address in IPv6?

Answer 15

They are used for communication within a local network segment.

They cannot be routed across different network segments and are automatically configured.

Question 16

True or False:

IPv6 can coexist with IPv4 in a network during the transition phase.

Answer 16

True

Dual-stack networks allow IPv4 and IPv6 to run simultaneously, facilitating the transition from IPv4 to IPv6.

Question 17

What does the ”::” notation represent in an IPv6 address?

Answer 17

One or more groups of 16-bit zeros.

This notation helps shorten the representation of long IPv6 addresses by omitting the zero sections.

Question 18

How does IPv6 achieve more efficient routing compared to IPv4?

Answer 18

By reducing routing table sizes and eliminating NAT.

IPv6 achieves more efficient routing by using hierarchical addressing, which reduces the number of entries in routing tables.

Unlike IPv4, IPv6 does not require Network Address Translation (NAT) because of its larger address space, allowing for end-to-end connectivity.

Question 19

True or False:

IPv6 supports broadcast communication.

Answer 19

False

IPv6 does not use broadcast communication; instead, it uses multicast and anycast.

Question 20

Describe how to configure an IPv6 address on a Cisco router interface.

Answer 20

Use “ipv6 address [address] [prefix]” in interface configuration mode.

This command assigns an IPv6 address to the interface, enabling IPv6 routing.

Question 21

What does the IPv6 address 2001:0db8:1234::/48 represent?

Answer 21

A network with a /48 prefix.

The /48 prefix allows for subnetting and provides a large address space for the network.

Question 22

True or False:

The IPv6 address 0:0:0:0:0:0:0:1 is the loopback address.

Answer 22

True

The *loopback address *in IPv6 is written as ::1 and is used to test local network functionality.

Question 23

Fill in the blank:

The first 64 bits of an IPv6 address are typically used for ______ ______.

Answer 23

network prefix

The remaining 64 bits are used for the host portion, enabling multiple devices in a subnet.

Question 24

Define:

IPv6 forwarding

Answer 24

The process of routing IPv6 packets to their destination.

The router forwards packets based on its IPv6 routing table.

Question 25

# True or False: An IPv6 address **cannot be configured manually** on a device.

Answer 25

False ## Footnote IPv6 addresses can be configured *manually or automatically* using *SLAAC or DHCPv6*.

Question 26

# Define: IPv6 prefix

Answer 26

An **identifier** that defines the network portion of an IPv6 address. ## Footnote It’s similar to the *subnet mask in IPv4*, determining the size of the network and the available addresses.

Question 27

What is the **default prefix length** for most IPv6 subnets?

Answer 27

/64 ## Footnote The */64 prefix length* is the most commonly used for IPv6 subnets, providing 64 bits for hosts.

Question 28

How does IPv6 address prefix length **affect subnetting**?

Answer 28

A longer prefix length **reduces** the number of available host addresses. ## Footnote A prefix length of /64 allows for *18 quintillion possible host addresses*, while /128 provides a single address.

Question 29

Why is the /64 prefix **commonly used** in IPv6 addressing?

Answer 29

It is **ideal** for auto-configuration and routing. ## Footnote It enables *automatic address configuration* for devices using SLAAC and allows for simple routing.

Question 30

What is the significance of the **2000::/3 prefix** in IPv6?

Answer 30

It **designates global unicast addresses**, which are publicly routable. ## Footnote This block is used for devices that *need to be reachable* from any other device on the internet.

Question 31

# True or False: IPv6 link-local addresses can be **routed** over the internet.

Answer 31

False ## Footnote Link-local addresses (fe80::/10) are only valid *within the local network segment* and cannot be routed.

Question 32

What **prefix** does an IPv6 multicast address start with?

Answer 32

ff00::/8 ## Footnote *Multicast addresses* are used to send data to *multiple receivers* simultaneously.

Question 33

What is the **IPv6 prefix** for loopback addresses?

Answer 33

::1/128 ## Footnote The *loopback address* is used to test the local device’s network stack.

Question 34

# True or False: The 0::/8 prefix is a **valid range** for IPv6 addresses.

Answer 34

False ## Footnote The 0::/8 prefix is **reserved** and *not assigned to any valid addresses in IPv6.*

Question 35

How do you **enable IPv6 routing** on a Cisco router?

Answer 35

Use the **ipv6 unicast-routing** command. ## Footnote This **command** enables the router to forward IPv6 packets and support IPv6 address configuration.

Question 36

What is the command to **assign an IPv6 address** to an interface?

Answer 36

ipv6 address [address] [prefix] ## Footnote This **command** *configures the IPv6 address* and *prefix length* for the router interface.

Question 37

What command is used to **verify IPv6 address configuration** on an interface?

Answer 37

show ipv6 interface [interface] ## Footnote This **command** *shows the IPv6 address, prefix, and other details* for a specific interface.

Question 38

How do you **verify IPv6 routing** on a router?

Answer 38

show ipv6 route ## Footnote This command displays the *IPv6 routing table*, showing how IPv6 traffic will be **routed** based on the network's configuration.

Question 39

What is the purpose of the **ipv6 enable** command?

Answer 39

It enables **IPv6 processing** on an interface. ## Footnote It is **required** if you want the interface to be able to use IPv6, but doesn't configure an address on the interface.

Question 40

How many bits are **contained** in each field of an IPv6 address?

Answer 40

16 ## Footnote An IPv6 address **consists** of eight groups of *16-bit hexadecimal numbers.*