Address Exaustion and AutoConfig (w11) Flashcards
since classes AB and C are not used today, what is implemented instead
CIDR or classless interdomain routing
order these RIR, IANA and ISP’s/Users
from top down: IANA, RIR, ISP
who can ISP’s obtain IPv4 and 6 addresses from? what do they do?
they can obtain ipv4 from: reseller market and RIR
IPv6 from: RIR. Regional Internet Registry (RIR) manage the allocation and registration of internet number resources within a particular region of the world.
why were RFC 1918 addresses implemented?
was used to conserve IPv4 addresses, by creating addresses within a private network that would not be reachable by the internet.
which class is 10.0.0.0/8? 192.168.0.0/16? 172.16.0.0/12?
A,C,B
what is the downside with RFC 1918?
means that not every device is uniquely identifiable. harder for two hosts on seperate networks to communicate without an intermediary
what are three workarounds for RFC 1918?
NAT, ALG’s, IPv6
what is an alg, what are the downfalls?
alg will handle coms with the outside world for an application. alg’s have an RFC 1918 address and a globally unique address. Downfall is each app requires its own ALG protocol to be defined and implemented - no easy way for two hosts to communicate.
what is an example of an ALG?
a Proxy server
what is a NAT gateway? what does it do?
it acts as a relay. It re-writes the source IP address and source port on outgoing packets, then reverses this for the reply packets/
Advantages/disadvantages of NAT (network address translation)
adv. simple to implement, usable with UDP, TCP and ICMP. Only one implementation required for several apps
disadv. breaks peer to peer connections, does not allow in-bound connections, single point failure: if NAT breaks, all connections are then lost.
Can you multicast TCP packets?
No, TCP assumes single sender/receiver
statless vs staeful firewalls
stateless examine each packet, holds no memory. Stateful check if the packet is part of an existing flow of packets. is more expensive, requires more processing and memory
what do computers frequently need to know when mvong to a new network
a suitable IP address and mask to use
suitable default gateway
DNS server
Time server?
what is a bootrequest?
a request broadcasted by computer looking for network information. server replies with trans ID, supplying the computer with the relevant information, eg asigned IP, gatewaye, server
adv and disadv of BOOTP?
adv. good protocol for diskless booting (allows network to load operating system from server to pc without diskdrives)
disadv. not great if you already have operating system and only need IP address, router and DNS. no subnet mask?
what is DHCP?
is a network server which automatically provides and assigns IP addresses and other network parameters to allow communication.
when a DHCP server makes an offer, does it reserve the resources? until what happens?
DHCP reserves until it receives a DHCPREQUEST packet, which will confirm or deny that the client accepted the offer
Do clients keep their DHCP allocated resources forever? what happens if client turns off their computer?
no, clients are expected to renew the lease before it expires, as DHCP servers will return the resources to the “free” pool. Clients release the lease when they shutdown via a DHCPRELEASE packlet.
how ipv6 gives itself a unique address>
router multicasts the server prefix. client uses the prefix, and a randomly generatednumber to fill the hostID out.
what are properties of EUI-64 addresses?
useing mac address, inserting FFFE into the middle of this means 48 bit mac address now has the 64 bits needed to create the host id portion of the ipv6 address. the 7th bit is 1 in the host ID section, if the address is “universal’
privacy conserns in using MAC address in Host ID is mitigated by>
using a random number, changing that number regularly
slaac limitations
admin cannot assign pre-defined addresses
DHCPv6 vs DHCP
DHCPv6 leaves hosts to determine their own addresses. android phones do not support DHCPv6.
What is a link local address
address only valid for communications within the network segment
what is zeroconf?
advertises resources available on the local network. helps with ad hoc networks.
