Lesson 4 - Chapter 2: Network Addressing with IPv4 Flashcards
What is an IP address?
a unique identification number for a computer on a network
What do the parts of an IP address identify? (2)
IP addresses identify:
1. the network to which the host belongs to (Network ID)
2. the individual host within that network (Host ID)
What does IPv4 stand for?
Internet Protocol version 4
IPv4 addresses consist of how many sets of binary numbers?
4 sets of 8 binary numbers (4 x 8 binary numbers = 32 total binary numbers)
a group of 8 binary numbers is called what?
octets
11110000 (binary) = 240 (octet)
What is dotted decimal notation?
when the 4 sets of octets in an IPv4 address are separated by a period
No number in an IPv4 address can ever be greater than….? Why?
255, because the largest binary 8-digit number is 11111111 = 255
What does the NIC use to distinguish what part of an IP address identifies the Network ID and which identifies the Host?
NIC uses a value called the subnet mask
What does a subnet mask do?
A subnet mask blocks out/masks the network portion of an IP address
When comparing a subnet mask to the IP address, any part that’s all 255’s is what?
Example subnet mask of: 255.255.255.0
IP address: 192.168.4.33
the Network ID
(192.168.4)
When comparing a subnet mask to the IP address, any part that’s all 0’s is what?
Example subnet mask of: 255.255.255.0
IP address: 192.168.4.33
the Host ID
(33)
Every computer on a single LAN must have the same ___ ___ and a ___ ___ ___
every computer on a single LAN must have the same network ID and a unique host ID
What happens if 2 computers have the same IP address?
they won’t be able to talk to each other, and other computers won’t know where to send data
What is an IP conflict?
when 2 computers have the same IP address
How many total Host IP addresses are available?
254 addresses (ending in 1-254)
We can never have an IP address that ends with what two numbers?
IP addresses can never end in 0 or 255
What is classful addressing?
Determining the amount of unique host IDs available depending on the address class (A, B, or C)
(the class system is long gone)
Although the class system is long gone, it’s still common to see subnet masks with 1-3 groups of what number?
255
What is the current system of assigning IPv4 addresses and subnet masks called?
Classless Inter-Domain Routing (CIDR)
What does CIDR stand for?
Classless Inter-Domain Routing
With CIDR, network techs refer to the subnet mask by the number of…
1s that it contains
Example subnet mask:
11111111.11111111.11111111.00000000
would be /24
A /24 network ID offers up to how many host IDs?
254 host IDs
(remember, no IP address can end in 0 or 255 so only 1-254 is available)
With CIDR, how do you pronounce /24?
whack 24
You can’t use 0 for host IDs because…?
that’s the address of the subnet itself
What is an IPv4 loopback address? What is it assigned to?
the logical address assigned to the network adapter in a computer/device
(loopback usually refers to the NIC or its network adapter)
Why is the loopback address almost always the same on all network-enabled computers?
there’s a set standard for the loopback address range
On any single PC using IPv4 addressing, what is the loopback address likely to be?
the loopback address is likely to be 127.0.0.1 (but not always)
(same for other PCs on the same network, no issue because it loops back to itself)
Network-capable devices can have multiple network adapters which is referred to as?
being multi-homed
In which situation would a loopback address be different from the typical 127.0.0.1?
a network device has multiple network adapters (multi-homed) and is assigned a different loopback address
(127.0.0.0-127.255.255.255 range)
What are the 2 ways that devices get IP addresses?
- A DHCP server automatically assigns a dynamic IP address
- Technician sets up a static IP address (manually configured)
What does DHCP stand for?
Dynamic Host Configuration Protocol
What does a DHCP server do?
Automatically assigns an unused IP address to a host each time it connects to the network
What kind of DHCP servers do business and small home networks use? (2)
Business = dedicated DHCP server
Small home networks = basic DHCP server function built into the switch/router
What are the 4 steps involved in a device securing an IP address from a DHCP server?
The network
The DHCP
The device
Lease
- The network device wants to connect to the network, and sends out a broadcast message looking for a DHCP server
- The DHCP server answers, the device requests an IP address and is granted a temp lease on a particular IP address
- The device can ask for a renewal halfway through lease
- Lease expires when lease time runs out or the device shuts down
Who controls the lease time of an IP address?
the DHCP server
What command can you use at a command line interface to release or renew an IP address lease?
ipconfig
What is a static address? Is it permanent or temporary?
one that is (semi)permanently assigned to a particular device
(it doesn’t consult with the DHCP to see if its available, just uses it)
What should you make sure you do if you setup a device with a static IP address?
configure the DHCP server to avoid assigning that IP address to any other device
What is a DNS server?
an Internet server that translates IP addresses into domain names (google.com)
What is private network addressing?
each host is not directly connected to the Internet so they don’t need an IP address that is globally unique
(computers on a LAN, only the router has a direct connection to the ISP)
DHCP servers built into consumer-level routers are set up by default to assign what 3 IP address blocks?
192.168.0.0 - 192.168.255.255 (Private networks)
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
What does APIPA stand for?
Automatic Private IP Addressing
What does APIPA do? (What assigns it?)
The operating system assigns an IP address to the system automatically when the system cannot access a DHCP server to obtain an IP address
When using APIPA, the system can only communicate with other computers on the same subnet that use what?
the same IP address range (with the same subnet mask)
A computer with an APIPA IP address range indicates what?
if there’s an active DHCP server, it means there’s a problem connecting to it
What is the default gateway?
It’s the [first] LAN IP address assigned to the port on your router that your computer uses to send data anywhere outside your Network ID
Home broadband routers usually come preconfigured to use what IP address as the default gateway?
Avoid assigning this address to a host!
192.168.0.1
What’s the APIPA address range?
from 169.254.0.1 to 169.254.255.254
The IPv4 loopback address is?
127.0.0.1
What’s the private IP address range?
192.168.0.0 - 192.168.255.255
What’s the purpose of a loopback address?
Useful for testing because it loops back to itself
Private networks use what 3 ranges of reserved IPv4 addresses?
- 192.168.0.0 - 192.168.255.255
- 10.0.0.0 - 10.255.255.255
- 172.16.0.0 - 172.31.255.255
What is the default gateway?
the port on the router that connects to your LAN (it receives an IP address that’s part of the LAN address scheme)
