Chapter 7: TCP/IP Basics Flashcards Preview

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Flashcards in Chapter 7: TCP/IP Basics Deck (57):
1

Protocol Stack

The software installed on a system that enables a specific protocol suite to function

2

Internet Protocol (IP)

Works at the Internet layer, taking data chunks from the Transport layer, adding addressing, and creating the final IP packet.

3

ICMP

Internet Control Message Protocol (ICMP) is an error reporting and diagnostic utility and is considered a required part of any IP implementation.

4

ping

-Command used to query if a host is reachable
-Shows the round trip time (RTT) for the ICMP packet it sends

5

What is the structure of a simple IP header?

version -> 32 bits (Header Length) -> DSCP -> TTL -> Protocol

6

Version field of an IP header

Defines the IP address type, i.e. 4 for IPv4 and 6 for IPv6

7

Header Length field of an IP header

The total size of the IP portion of the packet, which happens to be 32 bits

8

DSCP field of an IP header

-Differentiated Services Code Point
-Contains data used by bandwidth-sensitive applications

9

TTL field of an IP packet

-Time To Live
-A counter that decrements by one every time a packet goes through a router.
-Usually 128, can't be higher than 256

10

Protocol field of an IP packet

Usually either TCP or UDP, and identifies what's encapsulated inside the packet

11

What percentage of TCP/IP applications use TCP?

~95%

12

ACK/NACK

TCP's communication rule that requires both the sending and receiving machines to acknowledge the other's presence and readiness to send and receive data.

13

Port Number

Used by systems to determine what application needs the received data.

14

Structure of a simple TCP header

Source p# -> Dest p# -> Sequence # -> ACK

15

Sequence Number and ACK fields of a TCP header

Enable the sending and receiving computers to keep track of the various pieces of data.

16

Flags

An optional portion of a header that gives both sides detailed info about the state of the connection

17

Checksum

A portion of a TCP header that checks it for errors

18

Application Layer Protocols

Used by TCP/IP applications to move data back and forth between servers and clients

19

Universal MAC Address

FF-FF-FF-FF-FF-FF

20

In Windows -> ipconfig
In UNIX/Linux/OSX -> ifconfig

Provide lots of info regarding a system's TCP/IP settings

21

Netword ID

The part of an IP address that every computer on a network starts with

22

Host ID

The part of an IP address that distinguishes each computer from each other

23

Default Gateway

-The IP address of the router that interconnects the LAN to a wider network.
-Usually the lowest host ID in the network

24

Subnet Mask

The 32 bit number used to divide the IP address of a host into its network ID and host ID.

25

ARP

-Address Resolution Protocol
-Used to determine the MAC address that corresponds to a particular IP address.

26

IANA

-Internet Assigned Numbers Authority
-Formed to track and disperse IP addresses

27

RIR

-Regional Internet Registry
-Parcels out IP address to large ISPs and major corporations
-Controlled by IANA

28

ARIN

-American Registry for Internet Numbers
-The RIR for North America

29

Class A

1-126

30

Class B

128-191

31

Class C

192-223

32

Class D

224-239

33

Class E

240-254

34

Subnetting

Taking a single class of IP addresses and chopping it up into multiple smaller groups

35

Calculating Hosts Formula

2^(# of zeroes in subnet mask) - 2

36

Calculating Subnets Formula

2^(# of ones added to the subnet mask)

37

Static Addressing

Typing in all of the IP info into each of your clients manually

38

What should you always do after statically assigning IP info?

Ping the IP address

39

Dynamic Host Configuration Protocol (DHCP)

Automatically assigns an IP address whenever a computer connects to the network

40

DHCP ports

UDP 67 (servers) and 68 (clients)

41

DHCP Client

A computer configured to use DHCP

42

When a DHCP client boots up, it automatically sends out a special ________________ over the broadcast address.

DHCP Discover Packet

43

DHCP server

A server running DHCP server software

44

When a DHCP client sends a DHCP server a DHCP Discover Request, it responds with a __________.

DHCP Offer

45

DHCP Scope

The range of IP address a DHCP server pulls from.

46

A DHCP Client sends out a _________ to accept a DHCP Offer.

DHCP Request

47

When a DHCP Client accepts a DHCP offer, the DHCP Server sends out a ____________.

DHCP Acknowledgement

48

DHCP Lease

Created by the DHCP server to allow a system requesting DHCP IP info to use that info for a certain amount of time.

49

Automatic Private IP Addressing (APIPA)

Enables DHCP clients to self-configure an IP address and subnet mask automatically when a DHCP server isn't available.

50

APIPA cannot issue a __________.

Default gateway

51

A situation where there probably is a DHCP problem

You can communicate with other computers on your network that came up after the DHCP server went down (since you all have APIPA addresses), but you can't get to the Internet or access computers that retain the DHCP-given address

52

Command to reestablish a DHCP lease in Windows

ipconfig /renew

53

Command to reestablish a DHCP lease in UNIX/Linux/OS X

sudo ifconfig eth0 up

54

Command to release a DHCP release in Windows

ipconfig /release

55

Command to release a DHCP release in UNIX/Linux/OS X

sudo ifconfig eth0 down

56

Loopback address

127.0.0.1

57

Private IP Address Ranges

10.0.0.0 through 10.255.255.255
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255