Chapter 7: TCP/IP Basics Flashcards

1
Q

Protocol Stack

A

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

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2
Q

Internet Protocol (IP)

A

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

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3
Q

ICMP

A

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

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4
Q

ping

A
  • Command used to query if a host is reachable

- Shows the round trip time (RTT) for the ICMP packet it sends

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5
Q

What is the structure of a simple IP header?

A

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

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6
Q

Version field of an IP header

A

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

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7
Q

Header Length field of an IP header

A

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

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8
Q

DSCP field of an IP header

A
  • Differentiated Services Code Point

- Contains data used by bandwidth-sensitive applications

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9
Q

TTL field of an IP packet

A
  • 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
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10
Q

Protocol field of an IP packet

A

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

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11
Q

What percentage of TCP/IP applications use TCP?

A

~95%

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12
Q

ACK/NACK

A

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.

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13
Q

Port Number

A

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

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14
Q

Structure of a simple TCP header

A

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

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15
Q

Sequence Number and ACK fields of a TCP header

A

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

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16
Q

Flags

A

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

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17
Q

Checksum

A

A portion of a TCP header that checks it for errors

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18
Q

Application Layer Protocols

A

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

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19
Q

Universal MAC Address

A

FF-FF-FF-FF-FF-FF

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20
Q

In Windows -> ipconfig

In UNIX/Linux/OSX -> ifconfig

A

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

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21
Q

Netword ID

A

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

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22
Q

Host ID

A

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

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23
Q

Default Gateway

A
  • The IP address of the router that interconnects the LAN to a wider network.
  • Usually the lowest host ID in the network
24
Q

Subnet Mask

A

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