2.1 Common Network Ports

Question 1

TCP 20

Answer 1

File Transfer Protocol: data transfer

Question 2

TCP 21

Answer 2

File Transfer Protocol: control port (establishes connection)

Question 3

TCP 22

Answer 3

SSH - Secure Shell: used to connect a remote device through terminal or command line. Encrypted

Question 4

TCP 23

Answer 4

Telnet - Telecommunication Network Protocol: login to devices remotely, unencrypted

Question 5

TCP 25

Answer 5

SMTP - Simple Mail Transfer Protocol: server to server email transfer
Outgoing mail server

Question 6

UDP 53

Answer 6

DNS - Domain Name System: converts names to IP addresses

Question 7

UDP 67 & 68

Answer 7

DHCP - Dynamic Host Configuration Pool: automated configuration of IP address, subnet mask and other settings.
67 for DHCP server to receive client requests
68 for DHCP client to send requests

Question 8

TCP 80

Answer 8

HTTP - Hypertext Transfer Protocol: data communication in web browser and other applications

Question 9

TCP 443

Answer 9

HTTPS: Hypertext Transfer Protocol Secure: web server communication with encryption

Question 10

TCP 110

Answer 10

POP3 - Post Office Protocol v3: used by email clients to receive emails from a mail server.
Basic mail transfer

Question 11

TCP 143

Answer 11

IMAP - Internet Message Access Protocol v4: used by email clients to receive emails.
More advanced email management.
Synchronization across numerous devices
ex. iPhone, iPad, and MacBook all accessing the same inbox

Question 12

UDP 137

Answer 12

NetBIOS Name Service: name registration, find devices in LAN using the registered name

SMB using NetBIOS

Question 13

UDP 138

Answer 13

NetBIOS Datagram Service

Question 14

UDP 139

Answer 14

NetBIOS Session Service: setup session and transfer data between devices

Question 15

TCP 445

Answer 15

SMB - Server Message Block: used for file sharing, printer sharing, and miscellaneous communications between devices on a network. Modern versions of Windows do not use NetBIOS

Question 16

UDP 161 & 162

Answer 16

SNMP - Simple Network Management Protocol: used to query devices to check for performance or any types of errors.
161: SNMP manager to agent
162: SNMP agent to manager

Question 17

TCP 389

Answer 17

LDAP - Lightweight Directory Access Protocol: store and retrieve info in a network directory

Question 18

TCP 3389

Answer 18

RDP - Remote Desktop Protocol: share a desktop from a remote location

Question 19

TCP vs UDP

Answer 19

TCP: connection based
- more reliable but slower
- retransmission of lost packets
UDP: connection-less
- prioritizes speed
- common for video streaming

Question 20

FTP (File Transfer Protocol)

Answer 20

TCP 20 and 21

Question 21

SSH (Secure Shell)

Answer 21

TCP 22

Question 22

Telnet

Answer 22

TCP 23

Question 23

SMTP (Simple Mail Transfer Protocol)

Answer 23

TCP 25

Question 24

DNS (Domain Name Server)

Answer 24

UDP 53

Question 25

DHCP (Dynamic Host Configuration Protocol):
For server receiving client requests

Answer 25

UDP 67

Question 26

DHCP (Dynamic Host Configuration Protocol):
For client sending requests

Answer 26

UDP 68

Question 27

HTTP (HyperText Transfer Protocol)

Answer 27

TCP 80

Question 28

HTTPS (HyperText Transfer Protocol Secure)

Answer 28

TCP 443

Question 29

POP3 (Post Office Protocol v3)

Answer 29

TCP 110

Question 30

IMAP (Internet Message Access Protocol)

Answer 30

TCP 143

Question 31

NetBIOS

Answer 31

UDP 137, 138, 139

Question 32

SMB (Server Message Block)

Answer 32

TCP 445

Question 33

SNMP (Simple Network Management Protocol):
Manager to agent

Answer 33

UDP 161

Question 34

SNMP (Simple Network Management Protocol):
Agent to managers

Answer 34

UDP 162

Question 35

LDAP (Lightweight Directory Access Protocol)

Answer 35

TCP 389

Question 36

RDP (Remote Desktop Protocol)

Answer 36

TCP 3389

Question 37

TFTP

Answer 37

Trivial File Transfer Protocol
Uses UDP 69 port