Address Exaustion and AutoConfig (w11)

Question 1

since classes AB and C are not used today, what is implemented instead

Answer 1

CIDR or classless interdomain routing

Question 2

order these RIR, IANA and ISP’s/Users

Answer 2

from top down: IANA, RIR, ISP

Question 3

who can ISP’s obtain IPv4 and 6 addresses from? what do they do?

Answer 3

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.

Question 4

why were RFC 1918 addresses implemented?

Answer 4

was used to conserve IPv4 addresses, by creating addresses within a private network that would not be reachable by the internet.

Question 5

which class is 10.0.0.0/8? 192.168.0.0/16? 172.16.0.0/12?

Answer 5

A,C,B

Question 6

what is the downside with RFC 1918?

Answer 6

means that not every device is uniquely identifiable. harder for two hosts on seperate networks to communicate without an intermediary

Question 7

what are three workarounds for RFC 1918?

Answer 7

NAT, ALG’s, IPv6

Question 8

what is an alg, what are the downfalls?

Answer 8

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.

Question 9

what is an example of an ALG?

Answer 9

a Proxy server

Question 10

what is a NAT gateway? what does it do?

Answer 10

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/

Question 11

Advantages/disadvantages of NAT (network address translation)

Answer 11

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.

Question 12

Can you multicast TCP packets?

Answer 12

No, TCP assumes single sender/receiver

Question 13

statless vs staeful firewalls

Answer 13

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

Question 14

what do computers frequently need to know when mvong to a new network

Answer 14

a suitable IP address and mask to use
suitable default gateway
DNS server
Time server?

Question 15

what is a bootrequest?

Answer 15

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

Question 16

adv and disadv of BOOTP?

Answer 16

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?

Question 17

what is DHCP?

Answer 17

is a network server which automatically provides and assigns IP addresses and other network parameters to allow communication.

Question 18

when a DHCP server makes an offer, does it reserve the resources? until what happens?

Answer 18

DHCP reserves until it receives a DHCPREQUEST packet, which will confirm or deny that the client accepted the offer

Question 19

Do clients keep their DHCP allocated resources forever? what happens if client turns off their computer?

Answer 19

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.

Question 20

how ipv6 gives itself a unique address>

Answer 20

router multicasts the server prefix. client uses the prefix, and a randomly generatednumber to fill the hostID out.

Question 21

what are properties of EUI-64 addresses?

Answer 21

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’

Question 22

privacy conserns in using MAC address in Host ID is mitigated by>

Answer 22

using a random number, changing that number regularly

Question 23

slaac limitations

Answer 23

admin cannot assign pre-defined addresses

Question 24

DHCPv6 vs DHCP

Answer 24

DHCPv6 leaves hosts to determine their own addresses. android phones do not support DHCPv6.

Question 25

What is a link local address

Answer 25

address only valid for communications within the network segment

Question 26

what is zeroconf?

Answer 26

advertises resources available on the local network. helps with ad hoc networks.