Chapter 6 - TCP/IP Basics

Question 1

TTL

Answer 1

Time to Live
Field in an IP packet that prevents it from indefinitely spinning through the internet by using a counter that decrements by one every time a packet goes through a router

Question 2

TCP Three Way Handshake

Answer 2

Sending and receiving machines acknowledge each other’s presence and readiness to send and receive data
SYN
SYN-ACK
ACK

Question 3

Network ID

Answer 3

The portion of an IPv4 address that is similar for all hosts on the same LAN
Example- 202.120.10.x

Question 4

What does a router need to to connect LANs?

Answer 4

An IP address on every LAN it interfaces with- example:
FastEthernet0/0 192.168.1.1
FastEthernet0/1 192.168.2.1

Question 5

Default Gateway

Answer 5

The router interface that connects a single LAN to the router
Typically assigned the lowest host address on the network (ie 192.168.1.1)

Question 6

Subnet Mask

Answer 6

Tells sending computer whether the destination IP address is on the local network or on an external network

Question 7

ARP

Answer 7

Address Resolution Protocol
How a TCP/IP network figures out the MAC address based on the destination IP address

Question 8

Class A Network

Answer 8

First Decimal Value: 1-126
16,277,214 hosts per Network ID

Question 9

Class B Network

Answer 9

First Decimal Value: 128-191
65,534 hosts per Network ID

Question 10

Class C Network

Answer 10

First Decimal Value: 192-223
254 hosts per Network ID

Question 11

Class D Network

Answer 11

First Decimal Value: 224-239
Multicast

Question 12

Class E Network

Answer 12

First Decimal Value: 240-254
Experimental

Question 13

Subnetting

Answer 13

Taking a single class of IP addresses and chopping it up into multiple smaller groups
Enables you to separate a network for security and for bandwidth control

Question 14

Formula for calculating hosts on a subnet

Answer 14

2^x-2 where x = number of zeroes in subnet mask
2^8 - 2 = 254
2^16 -2 = 65,534

Question 15

DHCP

Answer 15

Dynamic Host Configuration Protocol
Automatically assigns an IP address whenever a computer connects to the network
Client makes request to DHCP server; DHCP server provides DHCP lease

Question 16

DHCP Scope

Answer 16

Range (or pool) of IP addresses assigned by Network Engineer

Question 17

DHCP Relay

Answer 17

Allows routers to forward DHCP requests from multiple LANs to the DHCP server rather than administering many different DHCP servers

Question 18

APIPA

Answer 18

Automatic Private IP Addressing
Clients are designed to generate an APIPA address if they don’t receive a response from a DHCP server
This allows the client to continue to communicate with other hosts on the same Network ID, but does not allow for external communication because APIPA cannot issue a Default Gateway

Question 19

DHCP Failover

Answer 19

Secondary DHCP server that will pick up the load if the first server fails

Question 20

Rogue DHCP Server

Answer 20

DHCP client will accept IP info from the first DHCP server that responds. This can happen if someone adds a home router to the network or if a bad actor is attacking the network
May give out IP addresses in the same scope as legit DHCP server, but change Default Gateway to intercept incoming and outgoing traffic

Question 21

127.0.0.1

Answer 21

Loopback Address
Sends packets to self

Question 22

Private IP Address Ranges

Answer 22

10.x.x.x
172.16.x.x - 172.31.x.x
192.168.x.x