ADVNET-DayBefore

Question 1

Does SLAAC provide a permanent address

Answer 1

No IPv6 SLAAC addresses can change and may use randomised values for privacy

Question 2

What is stateless DHCPv6 used for

Answer 2

To provide extra config like DNS and NTP alongside SLAAC without assigning addresses

Question 3

What does DORA stand for in DHCP

Answer 3

Discover Offer Request Acknowledge

Question 4

What does DAD stand for in IPv6

Answer 4

Duplicate Address Detection

Question 5

How many usable IPs in a /24 subnet

Answer 5

254 usable IPs

Question 6

What does the /27 prefix mean

Answer 6

27 bits are network bits leaving 5 for hosts which gives 30 usable addresses

Question 7

Why is the first IP in a subnet reserved

Answer 7

It represents the network address not assigned to any device

Question 8

What is the broadcast address used for

Answer 8

To send a message to all devices in a subnet

Question 9

What does PMTUD stand for

Answer 9

Path MTU Discovery

Question 10

Do IPv6 routers fragment packets

Answer 10

No fragmentation is handled by the sender using Path MTU Discovery

Question 11

How does IPv6 detect duplicate addresses

Answer 11

Using DAD Duplicate Address Detection

Question 12

What is the difference between PMTUD and longest prefix match

Answer 12

PMTUD finds smallest packet size longest prefix match is used in routing

Question 13

What is a recursive DNS query

Answer 13

A full query done by a client to a resolver expecting a complete answer

Question 14

What is an iterative DNS query

Answer 14

A partial query where the resolver asks each server step by step

Question 15

What does DNS TTL control

Answer 15

How long a DNS record is cached before rechecking

Question 16

What is a glue record in DNS

Answer 16

An IP address given with a nameserver to prevent circular lookups

Question 17

What is the Kaminsky attack

Answer 17

DNS cache poisoning using guessed 16-bit QIDs

Question 18

How does DNS amplification work

Answer 18

Small queries generate big responses sent to a spoofed victim IP

Question 19

What does DNSSEC protect against

Answer 19

Spoofing and cache poisoning by authenticating DNS records

Question 20

What do DoH and DoT protect against

Answer 20

Eavesdropping and tampering by encrypting DNS traffic

Question 21

Does TCP provide encryption

Answer 21

No encryption is added by TLS above TCP

Question 22

Is HTTP stateless

Answer 22

Yes each request is independent unless session data is manually handled

Question 23

Why is active FTP bad for NAT

Answer 23

Because the server opens a new connection back to the client which NAT often blocks

Question 24

Why is passive FTP better for NAT

Answer 24

Because the client opens both control and data connections

Question 25

What is the difference between FTP control and data channels

Answer 25

Control is for commands data is for file transfer

Question 26

What ICMP error is sent in IPv4 for large packets

Answer 26

Type 3 Code 4 Fragmentation Needed and DF set

Question 27

What ICMP error is sent in IPv6 for large packets

Answer 27

ICMPv6 Type 2 Packet Too Big

Question 28

Are gateway IPs reserved

Answer 28

No they are assigned from usable IP addresses

Question 29

What port does FTP use for control connection

Answer 29

Port 21

Question 30

What port does FTP use for active data connection

Answer 30

Port 20

Question 31

What is the purpose of the network address in a subnet

Answer 31

It defines the subnet and is not assignable to a host

Question 32

What is the purpose of the broadcast address

Answer 32

To send traffic to all hosts on the subnet

Question 33

IPv6 Link Local address range

Answer 33

fe80::/10

Question 34

IPv6 Multicast address range

Answer 34

ff00::/8

Question 35

IPv6 Unique Local address range

Answer 35

fc00::/7

Question 36

IPv6 Loopback address

Answer 36

::1

Question 37

IPv6 Unspecified address

Answer 37

::

Question 38

IPv6 Global Unicast range

Answer 38

2000::/3

Question 39

What are IP classes used for historically

Answer 39

They were used to divide the IPv4 address space into blocks of different sizes

Question 40

Why was classful addressing wasteful

Answer 40

Class A gave 16 million IPs to each org Class B gave 65k IPs Most orgs didn’t need that many

Question 41

Why did we move to CIDR

Answer 41

CIDR allows more efficient flexible address allocation instead of fixed size classes

Question 42

Do I need to memorise exact class boundaries

Answer 42

No just know they existed and were inefficient

Question 43

What are the class A B C default masks

Answer 43

Class A is slash 8 Class B is slash 16 Class C is slash 24

Question 44

How can I remember class sizes

Answer 44

A is massive B is medium C is small like a coffee order

Question 45

How were classes identified

Answer 45

By the starting bits Class A started with 0 B with 10 C with 110

Question 46

Is classful addressing still used today

Answer 46

No it’s obsolete CIDR replaced it in the 90s

Question 47

Why are there so few IPv4 addresses left

Answer 47

Because classful allocation was wasteful and IPv4 space is only 32 bits

Question 48

What is classful addressing

Answer 48

An old method of dividing IPv4 addresses into fixed-size blocks called classes

Question 49

How many main IP classes were used

Answer 49

Three main classes A B and C

Question 50

What was the IP range for Class A

Answer 50

0.0.0.0 to 127.255.255.255

Question 51

What subnet mask did Class A use by default

Answer 51

/8

Question 52

How many hosts per Class A network

Answer 52

About 16 million

Question 53

What was the IP range for Class B

Answer 53

128.0.0.0 to 191.255.255.255

Question 54

What subnet mask did Class B use by default

Answer 54

/16

Question 55

How many hosts per Class B network

Answer 55

About 65 thousand

Question 56

What was the IP range for Class C

Answer 56

192.0.0.0 to 223.255.255.255

Question 57

What subnet mask did Class C use by default

Answer 57

/24

Question 58

How many hosts per Class C network

Answer 58

About 254

Question 59

What is the problem with classful addressing

Answer 59

It wastes IP space because blocks were too large for most networks

Question 60

Why was Class A wasteful

Answer 60

Each org got 16 million IPs even if they only needed 10

Question 61

What replaced classful addressing

Answer 61

CIDR Classless Inter-Domain Routing

Question 62

Why is CIDR better than classful

Answer 62

CIDR allows variable-length subnetting and more efficient address use

Question 63

Is classful addressing still used today

Answer 63

No it is obsolete and replaced by CIDR

Question 64

Do I need to memorise exact class boundaries

Answer 64

No just know they existed and were inefficient

Question 65

What is VRRP and what problem does it solve

Answer 65

It lets multiple routers share a virtual IP so that if one fails another can take over without disruption

Question 66

What is Multipath TCP used for

Answer 66

To allow one TCP connection to run over multiple interfaces like WiFi and 4G with seamless failover

Question 67

Why is UPnP considered a security risk

Answer 67

It lets devices open NAT ports automatically without authentication which malware can exploit

Question 68

Why is logging difficult with CGNAT

Answer 68

Multiple users share one public IP so NAT must log ports and timestamps but logs grow huge and get deleted quickly

Question 69

Why does active FTP break with NAT

Answer 69

Because the server tries to open a new connection back to the client which NAT blocks

Question 70

Why is passive FTP more NAT friendly

Answer 70

Because the client opens both connections to the server so NAT is not confused

Question 71

Why is RTP used instead of TCP for media

Answer 71

Because RTP uses timestamps and sequence numbers and avoids retransmits for lower latency

Question 72

What is DNS compression and why is it used

Answer 72

It saves space in DNS responses by replacing repeated domain names with binary pointers

Question 73

What is stored in a UDP DNS message

Answer 73

A header a question and one or more answers plus optional authority and additional sections

Question 74

What is an RRset in DNS

Answer 74

A group of DNS records with the same name and type like multiple A records for the same domain

Question 75

Why must RRsets be cached as a whole

Answer 75

To ensure consistency and support load balancing and redundancy