IP Addressing Flashcards
IPv4 Address Classes
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
Private IPs
Can be used by anyone
Non-routable outside your LAN
NAT (Network Address Translation)
Allows for routing of private IPs through a public IP
Specialized IPs
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
Data Flows: Unicast
Data travels from a single source device to a single destination device
Data Flows: Multicast
Data travels from a single source device to multiple (but specific) destination devices
Data Flows: Broadcast
Data travels from a single source device to all devices on a destination networks
IP Address Components
IP Address
Subnet Mask
Default Gateway
Server Addresses (DNS, WINS) DNS: Convers domain names to IP addresses WINS: Converts NetBIOS names to IP addresses
DHCP Configuration
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
Zeroconf
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)
Subnetting
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
Purpose of Subnets
More efficient use of IP addresses than classful default
Enables separation of networks for security
Enables bandwidth control
CIDR
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)
VLSM (And protocols that support it)
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
IPv6 Benefits
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
IPv6 Address Structure
Each hexadecimal digit is 4-bits
128-bits total
No more than 32 hexadecimal digits
IPv6 Address Types
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
DHCP & IPv6
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
NDP
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
IPv6 Data Flows: Anycast
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
SLAAC
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)
EUI
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
RFC1918 Address
An IP address that is assigned by an enterprise organization to an internal host. These IP addresses are used in private networks
