IPv4 Addressing

Question 1

TCP/IP

Answer 1

Transmission Control Protocol/Internet Protocol

• Suite of protocols and standards that provide functionality of most networks.
• Provides logical addressing and packet forwarding between networks

Question 2

IP Header

Answer 2

Contains fields that manage logical addressing and forwarding function.

Question 3

Version Field (IP Header)

Answer 3

• Indicates version of IP in use

Question 4

Length (IP Header)

Answer 4

Indicates size of header and total packet size, including payload.
- Max theoretical size is 65,535 bytes, but actually much smaller to avoid fragmentation in Ethernet frames

Question 5

Protocol Field (IP Header)

Answer 5

• Describes what is encapsulated in payload so the host knows how to process it
• IP Protocol type value will indicate TCP (Transmission Control Protocol) or UDP (User Datagram Protocol)
• Some protocols run directly on IP instead of Transport Layer

Question 6

ICMP/1

Answer 6

Internet Control Message Protocol

• Runs directly on IP rather than on Transport layer
• used for status messaging and connectivity testing

Question 7

IGMP/2

Answer 7

Internet Group Messaging Protocol

• Runs directly on IP rather than on Transport layer
• used with multicasting

Question 8

GRE/45

Answer 8

Generic Routing Encapsulation

• Runs directly on IP rather than on Transport layer
• Used to tunnel packets accross an intermediate network.
• Used for some VPNs

Question 9

EIGRP/88 and OSPF/89

Answer 9

Enhanced Interior Gateway Routing and Open Shortest Path First

• Runs directly on IP rather than on Transport layer
• used by routers to exchange information about paths to remote networks

Question 10

Network Number (Network ID)

Answer 10

• Number common to all hosts on same IP network

Question 11

The Host Number (Host ID)

Answer 11

• Identifies a host within an IP network

Question 12

Network Mask

Answer 12

• Distinguishes network ID and Host ID in IP address
• Conceals host ID portion
• Where there is a 1 in the mask, corresponding digit in IP address is part of network ID
• 1s are always contiguous
• /notation indications number of bits set to 1 in net mask

Question 13

ARP

Answer 13

Address Resolution Protoclol

- Resolves IP Addresses to hardware addresses

Question 14

Unicast Packet

Answer 14

• Used by an IPv4 Host to communicate with single recipient

- Addressed to IP address of destination host

Question 15

Broadcast

Answer 15

• One means of communicating with multiple hosts
• Can be performed by sending packet to network or subnet broadcast address
• All hosts that share the same broadcast address receive the packet

Question 16

Multicasting

Answer 16

• Allows one host to send contend to other hosts that have identified as interested in receiving hosts content.
• Sent to special destination IP address configured for use with that multicast group
• At layer 2, delivered using special range of MAC addresses
• Intent to receive multicast is signaled by joining multicast group
• IGMP is typically used to configure this

Question 17

Anycast

Answer 17

• Means that a group of hosts has same IP Address
• When router forwards packet to anycast group it uses a prioritization algorithm to select host that is “closest”
• Allows for load balancing and failover

Question 18

VLANS

Answer 18

Virtual LANs

• Each interface on managed switch can be assigned a VLAN ID
• Different hosts on same cabling can be appear to be on different LAN segments
• Each VLAN is a separate BD

Question 19

Other uses for Subnets

Answer 19

• Security and administrative control

- Networks may use different physical or data link technologies

Question 20

Classful addressing

Answer 20

• Allocates network ID based on first Octet of IP address
• Can be identified using first octet:
  Class A: 1-126
  Class B: 128-191
  Class C: 192-223

Question 21

Public IP Address

Answer 21

• Can be used to establish connection with other public IP addresses and hosts
• Governed by IANA
• Administered by ISPs

Question 22

Private IP Addresses

Answer 22

• Non-routable ranges over the internet
• Any org can use private addresses and multiple use them simultaneously
• Can be used through NATing
• Or through a proxy server
• 10.0.0.0 - 10.255.255.255 (Class A Range)
• 172.16.0.0 - 172.31.255.255 (Class B Range)
• 192.168.0.0 - 192.168.255.255 (Clas C range)

Question 23

APIPA

Answer 23

Automatic Private IP Addressing

• Means for clients that could not reach DCHP to communicate over LAN
• If no response from DCHP, host sets its range to 169.254.1.1 - 169.254.254.254
• Type of addressing is referred to as link local

Question 24

Class D addresses

Answer 24

224. 0.0.0 - 239.255.255.255

- Used for multicasting

Question 25

Class E addresses

Answer 25

- 240.0.0.0 - 255.255.255.255 | - Experimental use and testing

Question 26

127.0.0.0 - 127.255.255.255

Answer 26

Loopback Addresses - Special address typically used to check that TCP/IP is installed corrected on local host. - Does not require physical interface to function.

Question 27

Subnet Addressing

Answer 27

- Using whole octet boundaries in Network ID can be inflexible - Has 3 hierarchical levels: network ID, subnet ID and host portion. - Bits from host portion are allocated as subnet address - Mask is only used within the IP network

Question 28

Network Address

Answer 28

- First address in network | - Cannot be assigned to host

Question 29

Broadcast Address

Answer 29

- Last address in network or subnet | - Cannot be used for hosts

Question 30

Default Gateway

Answer 30

- When destination IP address appears to be on different network or subnet, host forwards packet to here, instead of delivering locally