IP

Question 1

List network layer protocols that run directly on IP.

Answer 1

ICMP/1 (Internet control message protocol): Used for status messaging and connectivity testing.

IGMP/2 (internet group messaging protocol): Used with multicasting.

GRE/47 (Generic routing Encapsulation): Used to tunnel packets across an intermediate network. Used in some VPN implementations.

ESP/50 (encapsulating security payload): used with the encrypted form of IP (IPSec).

AH/51 (Authentication Header):used with the encrypted form of IP (IPSec).

EIGRP/88 (enhanced interior routing protocol):used by routers to exchange information about paths to remote networks.

OSPF/89 (Open Shortest Path First): used by routers to exchange information about paths to remote networks.

Question 2

What is a IP header?

Answer 2

Fields in a datagram used to identify source and destination IP addresses, protocol type, and other layer 3 properties.

Question 3

What does a IP header consist of?

Answer 3

Version field- indicates the IP version (IPV4 or 6)
Header length- not a fixed length.
Diffserve- quality of service information
Total length- the entire length
Identification, Flags, and Fragment Offset- If the packet is too big and needs to be broken up these break it up and label the order it is meant to be reassembled in.
TTL- amount of hops for data to travel
Protocol- Specifies the type of data encapsulated in the payload. Normally its either TCP (indicated by 6) or UDP (indicated by 17) traffic
Checksum- error checking
Source address
Destination address
Options- anything else that get added
Data- the data

Question 4

How do nodes from different subnets communicate?

Answer 4

via the router
if they are in the same subnet they can talk to each other directly.

Question 5

What is ARP and what does it do?

Answer 5

Access resolution protocol
resolves a IPv4 address into a hardware MAC address.
Used to make a network more efficient.

Question 6

What are the 2 types of ARP entries and what is the difference?

Answer 6

Dynamic: A dynamic entry is created automatically when a device sends out a broadcast message out on the network. Not permanent, gets flushed out periodically

Static: When a IP to MAC address is manually entered on the CLI. Used to reduce any unnecessary ARP broadcast traffic on the network.

Question 7

How does unicast work?

Answer 7

Used when a host wants to sent a packet to a single recipient.
A unicast packet is sent addressed to the IP address of the destination host.

Question 8

How does broadcast work?

Answer 8

Used to address multiple hosts.
performed by sending a packet to the network or subnets broadcast address.
All hosts in the same broadcast address will receive the packet

Question 9

How does multicast work?

Answer 9

Allows a host to send content to other hosts that have identifies themselves as interested in receiving the hosts contents.
The intent to receive multicast from a particular host is signaled by joining a multicast group, IGMP (Internet Group Management Protocol) is typically used to configure this.
Multicast addresses are in the range of 224.0.0.0 to 239.255.255.255.

Question 10

How does anycast work?

Answer 10

A group of host is configured to the same IP address and when a router forwards a packet to a anycast group it uses a prioritization algorithm and metrics to select the host that is “closest” and will receive the packet quickest.
Used a lot with servers, allows for load balancing and failover between server hosts sharing the IP address.
Anycast forwarding is handled by routers, typically using a dynamic routing protocol, such as Border Gateway Protocol (BGP).

Question 11

What is the maximum theoretical size of a IPv4 packet?

Answer 11

65535 bytes
The limit is set by the total length field in the IPv4 header, which specifies the total size of the packet including the header and the payload.

Question 12

What is classless subnetting?

Answer 12

IP networks and subnet IDs that are defined by network masks.
AKA CIDR addressing.

Question 13

What is classful subnetting?

Answer 13

Classful addressing allocates a network ID based on the first octet of the IP address.
Divides IP addresses into fixed classes.

Question 14

Tell me about class A networks.

Answer 14

Supports only 126 networks
Supports 16,777,214 hosts
First octet range of 1-126

Question 15

Tell me about Class B networks.

Answer 15

Supports 16,384 networks
Supports 65,534 host
First octet range of 128-191

Question 16

Tell me about class C networks.

Answer 16

support 2,097,152 networks
supports 254 hosts
first octet range of 192-223

Question 17

what does 127.0.0.0/8 ip address do?

Answer 17

used for loopback testing.
Its a special address typically used to check that TCP/IP is correctly installed on the local host

Question 18

what does 0.0.0.0/8 IP address do?

Answer 18

Used when a specific address is unknown. This is typically used as a source address by a client seeking a DHCP lease.

Question 19

What is a private IP address?

Answer 19

IP addresses designated for use on private networks only.

Question 20

What is a public IP address?

Answer 20

An IP address that can establish a connection with other public IP networks and hosts over the Internet

Question 21

What is class A, B and C private IP address ranges?

Answer 21

Class A: 10.0.0.0 to 10.255.255.255
Class B: 172.16.0.0 to 172.31.255.255
Class C: 192.168.0.0 to 192.168.255.255

Question 22

What are the 2 ways internet access can be facilitated for hosts using a private IP?

Answer 22

Through a router configured with a single valid public IP address or a block of valid public IP addresses. The router uses NAT to translate between the public and private IPs

Through a proxy server that fulfills requests for internet resources on behalf of clients. The proxy must be configured with a public IP address on the external-facing interface.

Question 23

Who is the private IP address pool defined by?

Answer 23

RFC 1918

Question 24

What are Class D and Class E IP addresses used for and what is their range?

Answer 24

Class D addresses (224.0.0.0 through 239.255.255.255) are used for multicasting.

Class E addresses (240.0.0.0 through 255.255.255.255) are reserved for experimental use and testing.

Question 25

What is the 255.255.255 used for?

Answer 25

Used to broadcast to the local network when the local network address is not known.

Question 26

What addresses are set aside for a variety of special purposes?

Answer 26

64.0.0.0/10, 192.0.0.0/24, 192.88.99.0/24, 198.18.0.0/15

Question 27

What addresses are set aside for use in documentation and examples?

Answer 27

192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24

Question 28

What factors must be weighed when planning a IPv4 network addressing scheme?

Answer 28

The number of IP networks and subnetworks required must be considered. The number of hosts per subnet that must be supported must be considered. The network ID must be from a valid public or a private range (not from the loopback, link local reserved range, multicast range, or reserved/experimental range, for instance). The network and/or host IDs cannot be all 1s in binary because this is reserved for broadcasts. The network and/or host ID cannot be all 0s in binary; 0 means "this network." Each host ID must be unique on the IP network or subnet. The network ID must be unique on the Internet (if you are using a public addressing scheme) or on your internal system of internetworks (if you are using a private addressing scheme).

Question 29

What 2 problems does classless addressing solve?

Answer 29

1. that network address especially class B were becoming scarce. 2. Near exponential growth in internet routing tables. Also supports subnet addressing.

Question 30

What is CIDR

Answer 30

Classless inter domain routing. Uses bits normally assigned to the network ID to mask the complexity of the subnet and host addressing scheme within that network. Sometimes described as supernetting.

Question 31

What is VLSM and what does it allow you to do?

Answer 31

Variable length subnet masking. Uses network prefixes of different lengths within an IP network to create subnets of different sizes. Allows different length subnetmasks(netmasks) to be used within the same IP network, allowing more flexibility in the design process.

Question 32

What is IPv6 addressing scheme and how many unique addresses does it allow?

Answer 32

Uses 128 bit addressing Has space for 340 undecillion unique addresses.

Question 33

What is canonical notation?

Answer 33

Compressing the IPv6 address

Question 34

How is a IPv6 address broken up?

Answer 34

The first 64 bits are the network ID and the last 64 bits are used for Interface ID (the equivalent of host ID).

Question 35

What type of addressing can and cant IPv6 use?

Answer 35

Its can use multicast, anycast and unicast It doesn't use broadcast addressing.

Question 36

What is IPv6 equivalent of IPv4 public addresses?

Answer 36

Global addressing.

Question 37

What is EUI-64?

Answer 37

a method used in IPV6 addresses to create a 64 bit interface ID from a devices 48 bit MAC address. Inserts FFFE in the middle?????

Question 38

What is a link local address?

Answer 38

starts with fe80:: Equivalent to IPv4 APIPA address but a IPv6 host is always configured with a link local address. Used to communicate within a local network segment.

Question 39

What does MLD do?

Answer 39

Multicast listener Discovery protocol Allows nodes to join a multicast group and discover if members of a group are present on a local subnet.

Question 40

What does IPv6 use for ARP?

Answer 40

Replaces ARP with Neighbor Discovery (ND) protocol.

Question 41

What does it mean to dual stack?

Answer 41

That hosts and routers can run both IPv4 and IPv6 simultaneously and communicate with devices configured with either type of address.

Question 42

What is tunneling for IP addresses and how does it work?

Answer 42

Can be used to deliver IPV6 packets over a IPv4 network options include: 6to4 replaced by IPv6 Rapid Deployment (6RD) Teredo protocol GRE (Generic routing encapsulation)

Question 43

What is NAT64

Answer 43

An IPv6 host address uses the prefix 64:ff9b::/96 plus the 32 bit IPv4 routing address. When the packet reaches the IPv4 gateway router it strips the prefix and forwards the packet using IPv4 headers

Question 44

What is the IPv6 loopback address?

Answer 44

0:0:0:0:0:0:0:1 often expressed as ::1

Question 45

What are some IP configuration issues?

Answer 45

Having an incorrect IP address or incorrect Subnet Mask

Question 46

What can you use to solved duplicate IP and MAC address issues?

Answer 46

ping and arp -a to examine the ARP cache.

Question 47

What is the general ping sequence to identify connectivity issues?

Answer 47

Ping loopback Ping Host Ping Gateway Ping Remote Host Ping Host name Establish Session.