IP Addresses Flashcards
What is an IP Address?
An IP address is a unique identifier number assigned to every device on the internet. There are therefore billions of different ones!
Why is IPv4 being phased out?
Because IPv4 uses 32-bit (4 blocks of 8 bits) long IP addresses there are around 4 billion possible combinations/unique IP addresses to be assigned. As there are many more devices than this on the internet now the IPv4 Address Pool is nearly depleted (empty).
To remedy this IPv6 was created, which uses 124-bit long IP addresses to create a possible 340 TRILLION unique IP’s.
IPv4 and IPv6 addresses can connect to each other.
How many bits are in a byte?
8 bits to a byte.
1 bit is a 1 or a 0 - binary. The smallest unit of data that can be stored/processed by a computer.
What is the difference between a byte and an octet?
There isn’t one! Synonymous. Both are made of 8 (hence oct-et) bits. Which are 1 or 0 - binary. The smallest bit of a data is a bit (0/1)
Which IP address version uses alphanumeric (numbers and letters) to form it’s unique identifiers/addresses?
IPv6 (128 bits) uses alphanumeric addressing whereas IPv4 (32 bits) just uses numbers.
What is a default gateway?
The default gateway is the network device (usually a router) that connects your subnet to the internet/ISP. You need the address of this device (Default Gateway/Default Gateway Address).
All traffic between the subnet and wider internet is routed/sent through and received through the Default Gateway (router).
What server is responsible for converting IP addresses (numbers IPv4/alphanumericals IPv6) to Domain Names and vice versa?
The Domain Name System (DNS - udp/53) server converts IP’s into domain names and back again so that users don’t have to remember long number/alphanumeric sequences to connect to each website/device on the internet.
You configure two DNS Servers in your IP configuration so if one is not available (not working, like if google is down) you can use the other and still get online.
Why do you use at least 2 DNS servers when configuring DNS on a device?
You configure two DNS Servers in your IP configuration so if one is not available (not working, like if google is down) you can use the other and still get online.
What was BOOTP and what protocol was developed to replace it/improve it?
BOOTP (1993) - bootstrap protocol was developed to automatically assign IP addresses to devices on a network. However, it wasn’t fully automatic as some manual configuration was still required and it didn’t track when a device left the network so the IP was not able to be reused.
It was replaced by DHCP (1997) which is fully automatic bla bla bla and utilises the DORA handshake/process to assign a new network device an IP from it’s server pool.
What are the four steps of DORA used by the DHCP server to assign an IP to a new device on the network?
Discover - the new device scans for/finds DHCP server/s on it’s network (upon powering on).
Offer - the DHCP server/s offers/gives the device an IP address/es.
Receive - the device receives/confirms/accepts/picks the IP address.
Acknowledge - the DHCP server acknowledges the receipt of the IP address and sends over all necessary configuration to the device to join the network.
DORA is a stepped conversation starting with the device and then to the server then the device then the server. Like a tennis match.
What is a reserved IP address?
An IP address that is reserved/set aside for a specific device/MAC address. Reserved IP addressed are configured on the DHCP server so that whenever it recognises that a specific MAC address (e.g. a particular printer) has joined the network it assigns it the reserved IP address.
What is APIPA?
When a DHCP server is not available on a network then APIPA - Automatic Private IP Addressing - assigns a Private IP address to the device thus allowing it access to the network (any devices on the network that ALSO have an APIPA address). DOESN’T ALLOW YOU TO CONNECT TO THE INTERNET.
The IP address assigned will be in the range of 169.254.1.0 through 169.254.254.255.
If you see an IP within this range then you can automatically assume that a DHCP server is not available on the server.
It uses ARP - Address Resolution Protocol to map dynamic IP addresses to MAC addresses on the network. (DHCP also uses ARP)
What server can you assume is not on network if you see a device has an IP address within the range of:
169.254.1.0 to 169.254.254.255
That range of IP addresses is reserved for APIPA and therefore you can assume that there is NO DHCP server on the network.
What two parts does a subnet mask split an IP address into?
The first part of the address is the Network address/Identifier for what specific network a device is a part of/connected to.
The second (last part) of the address is the Host/Device identifier.
The first part is as long as there are 1’s. So when the subnet mask switches from 1’s to 0’s that is where the Network Address is SEPARATED from the Host Address part of the IP address.
CIDR notation is how many ones there are before you change to 0’s.
What are the benefits of subnetting (partitioning networks into smaller subnets (sub-networks))?
Splitting networks into smaller more manageable networks (Subnetting) allow the following benefits:
MANAGEABILITY
It reduces network complexity, reduces broadcast volume and therefore network traffic.
