IP Addressing

Question 1

IPv4 Address Classes

Answer 1

Class A: 1-126 | 255.0.0.0 | /8
Class B: 128-191 | 255.255.0.0 | /16
Class C: 192-223 | 255.255.255.0 | /24
Class D 224-239 | n/a | n/a

Question 2

Private IPs

Answer 2

Can be used by anyone
Non-routable outside your LAN

NAT (Network Address Translation)
Allows for routing of private IPs through a public IP

Question 3

Specialized IPs

Answer 3

Loopback Address (127.X.X.X range)
Usually 127.0.0.1
Used for device itself for testing

APIPA
Dynamically assigned by OS when DHCP is unavailable
169.254.X.X

Question 4

Data Flows: Unicast

Answer 4

Data travels from a single source device to a single destination device

Question 5

Data Flows: Multicast

Answer 5

Data travels from a single source device to multiple (but specific) destination devices

Question 6

Data Flows: Broadcast

Answer 6

Data travels from a single source device to all devices on a destination networks

Question 7

IP Address Components

Answer 7

IP Address
Subnet Mask
Default Gateway

Server Addresses (DNS, WINS)
DNS: Convers domain names to IP addresses
WINS: Converts NetBIOS names to IP addresses

Question 8

DHCP Configuration

Answer 8

Dynamic Host Control Protocol Configuration

Based on older Bootstrap Protocol (BOOTP)
Required static database of IPs & MACs to assign

Service assigns IP from an assignable pool (scope)

IP Address Management
Software used to manage IPs being assigned

Question 9

Zeroconf

Answer 9

Newer tech based on APIPA

Assigns link-local IPs

Resolving computer names to IPs without DNS server
mDNS (Multicast Domain Name Server)

Locating network services
(SLP, SSDP, DNS-SD)

Question 10

Subnetting

Answer 10

Default classful subnet masks are rarely an optimal choice for a subnet size

Subnets can be modified using subnet masks to create networks that are better scoped

Creating a subnet involves borrowing bits from the original host portion and adding them to the network portion

Question 11

Purpose of Subnets

Answer 11

More efficient use of IP addresses than classful default
Enables separation of networks for security
Enables bandwidth control

Question 12

CIDR

Answer 12

Classless Interdomain Routing
Instead of advertising multiple individual routes, the routes can be summarized & advertised as a single route

Used to summarize contiguous networks (route aggregation)

Question 13

VLSM (And protocols that support it)

Answer 13

Variable-Length Subnet Masking
Allows subnets of various sizes to be used

Requires routing protocol that supports it
(RIPv2, OSPF, IS-IS, EIGRP, BGP)

Basically, subnetting subnets
Without VLSM, all subnets would have to be the same size

Question 14

IPv6 Benefits

Answer 14

No broadcasts

No fragmentation
Performs MTU (maximum transmission units) discovery for each session

Can coexist with IPv4 during transition (dual stack)
IPv6 over IPv4 (tunneling over IPv4)

Simplified header

Question 15

IPv6 Address Structure

Answer 15

Each hexadecimal digit is 4-bits
128-bits total
No more than 32 hexadecimal digits

Question 16

IPv6 Address Types

Answer 16

Globally routable unicast addresses
Begins with 2000 to 3999
(Similar to IPv4 Class A/B/C)

Link-local address (Unicast)
Begins with FE80
(Similar to private IPv4 addresses)

Multicast address
Begins with FF

Question 17

DHCP & IPv6

Answer 17

IPv6 uses SLAAC (no need for DHCP)

If you want to use DHCP: DHCPv6 protocol

IPv6 uses NDP (Neighbor Discovery Protocol) to learn the layer 2 addresses on the network

Question 18

NDP

Answer 18

Neighbor Discovery Protocol
Used to learn layer 2 addresses on network

Router Solicitation
Hosts send message to locate routers on link

Router Advertisement
Routers advertise their presence periodically and in response to solicitation

Neighbor Solicitation
Used by nodes to determine link layer addresses

Neighbor Advertisement
Used by nodes to respond to solicitation messages

Redirect
Routers informing host of better first-hop routers

Question 19

IPv6 Data Flows: Anycast

Answer 19

Designed to let one host initiate the efficient updating of router tables for a group of hosts

IPv6 can determine which gateway host is closest & sends the packets to that host as though it were a unicast communication

That host can anycast to another host in the group until all routing tables are updated

Data travels from single source device to the device nearest to multiple (but specific) destination devices

Question 20

SLAAC

Answer 20

Stateless Address Autoconfiguration:
Discovers the current network that an interface is located on & then selects its own host ID based on its MAC using the EUI64 process

Eliminates need to obtain addresses or other config info from a central server (Ex: No need for DHCP)

(EUI = Extended Unique Identifier)

Question 21

EUI

Answer 21

Extended Unique Identifier:
Allows a host to assign itself a unique 64-bit IPv6 interface identifier (EUI-64)

Splits 48-bit MAC and puts 16-bits in between (FF FE)

Ex:
MAC - 00 21 2F B5 6E 10
EUI - 00 21 2F FF FE B5 6E 10

Question 22

RFC1918 Address

Answer 22

An IP address that is assigned by an enterprise organization to an internal host. These IP addresses are used in private networks