IP addresses Flashcards
(32 cards)
what does IPV4 use
octets(group of 8 bits) and its a 32 bit number
summarise unusable/reserved addresses
Some IP addresses cannot be used for individual devices or hosts on a network.
127.x.x.x is the loopback range, used for diagnostics on the local machine, not routable outside the device.
x.x.x.0 is the network identifier (network address) for the subnet — it identifies the whole network, not a host.
x.x.x.255 is the broadcast address on that subnet — used to send data to all hosts simultaneously.
x.x.x.1 is commonly used as the default router/gateway address, but this can vary depending on network setup.
parts of an IP address
networkID - left hand bits used to define the network where nodes are communicating
HostID - right hand bits, used to identify the nodes on the network
summarise classful addressing
Each class has fixed network and host portions.
classful vs classless addressing
classful : number of hostID’s are fixed, the use of the suffix “/24” enables IP addresses to be used with varying proportions of host and network IDs
classless: number of hostID are variable
summarise subnet masking
- a subnet mask is used with an IP add to identify the 2 unique parts of the address
- subnet mask has all network ID bits set to 1, and all host IDs set to 0
- bitwise AND is used with the IP and the network is identified
what is subnetting and why is it used
- the process of dividing a large network into smaller, more manageable sub-networks, or subnets
- reducing traffic and increasing control.
advantages of subnetting
- improves efficiency by routing data through one segment only
- reduces the size of the broadcast domain, which can improve security
- can reduce data collisions
public vs private IPs
Public IP: globally unique, routable over the internet.
Private IP: used within LANs, not routable on the internet.
- Not allocated centrally
- impossible to connect
to over Internet // fromoutside
network
following are considered private:
- 10.0.0.1 - 10.255.255
advantages of private IPs
Conserve public IPs: Many devices can use private IPs internally without needing public ones.
Enhance security: Private IPs are not directly accessible from the internet, reducing exposure.
Allow network flexibility: Private IP ranges can be reused in different networks without conflict.
Simplify internal network management: Easier to organize and control devices inside a local network.
Support NAT functionality: Private IPs work with NAT to connect to the internet via a shared public IP.
number of possible hosts
2^32 - 2
because they cane end in 255 or 0
why is network address translation (NAT) used
Conserves public IP addresses by allowing multiple devices to share one public IP.
Enhances security by hiding internal IP addresses from the external network.
Enables use of private IP addresses within local networks.
Allows communication between different IP address schemes (private and public).
Simplifies IP address management within an organization.
advantages of NAT
allows a single public IP address to be shared by any number of hosts with a private IP
Conserves IP addresses: Allows multiple devices on a local network to share a single public IP address.
Improves security: Hides internal IP addresses from external networks, reducing attack surface.
Enables private networks: Allows use of private IP addresses internally without conflict on the internet.
Simplifies IP management: Internal IPs can remain unchanged even if the external IP changes.
Supports IP address reuse: Private IP addresses can be reused across different networks.
NAT process
- the translation device records the source and destination socket address for each request
- it then communicates on the hosts with the destination IP address
- when a response returns, it is passed back to the host that made the original request
what is port forwarding
- a networking technique that allows external devices to access services on a private network
what is the purpose of a DHCP system
to automate the configuration of hosts connecting to a TCIP/IP network
advantages of a dhcp system
- reduces the need for expert knowledge when configuring a host
- reduced the time required to configure host
- facilitates efficient use of a limited pool of IP addresses
how does a DHCP system work
- The host sends a request to discover a DHCP server
- DHCP servers offer configuration to host
- host accepts offer of configuration from server
- DHCP server confirms that configuration has been allocated to host.
- The host configures its network interface using the IP address and configuration details provided by the server.
explain how an external router would be configured so that a web server can be accessed by computers outside of the network
- traffic arriving on the HTTP port must be forwarded by
- the external router to the IP address of the web server
Explain how:
* Computer A will use a subnet mask to determine whether or not it can send the
packet directly to Computer B across the LAN or if the packet must be sent via the
Internet
- AND operation of subnet mask with Computer A’s IP address
- AND operation of subnet mask with Computer B’s IP address
- result (of each AND operation) is the network/subnet ID
- network/subnet IDs compared
- as they are different, then packet must be sent via gateway, Computer B is not on the same subnet
- if they were the same, then Computer B
is on the same subnet.
explain how a packet will be routed across the Internet
- hierarchical organisation of routers
- path to take selected by each router
- (possible) repackaging of packet to use different protocol
- use of router tables to determine next hop
- router decrementing “time to live” of packet
- route determined using IP addresses
how can the checksum be used to determine if the received packet has been changed
during the transmission.
checksum produced when packet transmitted
* (hash) value calculated from packet contents
* this value appended to packet
* computer B recalculates checksum
* received and calculate checksum compared
* if these match packet contents/data are accurate . if these differ the data has been
changed // if these differ there is an error in the data.
explain how two or more computers connected to the Internet can have the same IP address and still communicate with each other
- the computers have private IP addresses
- so NAT will be performed
- so that the computers can communicate on the internet
reasons why IPv6 has been introduced to replace IPv4
- There are not enough (unique) addresses in IPv4
- Eliminate need for NAT / network address translation
- more efficient routing is possible;
- Improved facilities for multicasting;
- Automatic configuration possible without DHCP;
- Allows bigger packet sizes;
