220-1201 · Original practice content · Last reviewed October 3, 2026

Networking A+ Core 1 Practice Questions

Connect networking fundamentals to practical small-office and home-office setup decisions.

Core 1: up to 90 questions in 90 minutes. Passing score: 675 on a 100–900 scale. Both Core 1 and Core 2 are required for CompTIA A+.

These short multiple-choice samples report practice accuracy, not official scaled scores, and do not simulate interactive performance-based questions.

This domain accounts for 23% of Core 1. Topics: TCP/IP, ports and protocols, IP addressing, wireless standards, network devices, and SOHO configuration.

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Domain sample questions with answers

Networking

Sample question 1

A technician needs to allow Remote Desktop Protocol (RDP) connections through a firewall. Which port must be opened?

  1. 22
  2. 443
  3. 445
  4. 3389
Show correct answer and explanation

Correct answer: D. 3389

D is correct because RDP uses port 3389. A is used by SSH for secure command-line remote access. B is used by HTTPS for secure web traffic. C is used by SMB for Windows file and printer sharing.

Networking

Sample question 2

A network administrator wants to manage a switch through an encrypted command-line session. Which port does this connection use by default?

  1. 22
  2. 23
  3. 25
  4. 389
Show correct answer and explanation

Correct answer: A. 22

A is correct because SSH provides encrypted command-line access and listens on TCP port 22. B is used by Telnet, which sends the session, including passwords, in plaintext. C is used by SMTP to send email between mail servers. D is used by LDAP to query directory services.

Networking

Sample question 3

Which remote access protocol uses port 23 and sends all data, including credentials, as plaintext?

  1. HTTPS
  2. SSH
  3. RDP
  4. Telnet
Show correct answer and explanation

Correct answer: D. Telnet

D is correct because Telnet uses port 23 and does not encrypt the session, so credentials can be captured on the network. A uses port 443 and encrypts web traffic with TLS. B uses port 22 and encrypts the entire session. C uses port 3389 and encrypts the graphical remote desktop session.

Networking

Sample question 4

A small business hosts an internal website that is served without encryption. Which port must the web server accept connections on by default?

  1. 80
  2. 110
  3. 143
  4. 443
Show correct answer and explanation

Correct answer: A. 80

A is correct because HTTP, the unencrypted web protocol, uses TCP port 80 by default. B is used by POP3 to download email from a mail server. C is used by IMAP to access email stored on a mail server. D is used by HTTPS, the encrypted version of HTTP.

Networking

Sample question 5

Which port does Simple Mail Transfer Protocol (SMTP) use by default to send email between mail servers?

  1. 25
  2. 53
  3. 110
  4. 143
Show correct answer and explanation

Correct answer: A. 25

A is correct because SMTP uses TCP port 25 to transfer outgoing mail between servers. B is used by DNS for name resolution. C is used by POP3 to retrieve email, not to send it. D is used by IMAP to retrieve and manage email, not to send it.

Networking

Sample question 6

A user reads email on a phone, a laptop, and a desktop and wants all messages and folders to stay in sync on the server. Which protocol should the mail client use to retrieve mail?

  1. SMTP on port 25
  2. LDAP on port 389
  3. POP3 on port 110
  4. IMAP on port 143
Show correct answer and explanation

Correct answer: D. IMAP on port 143

D is correct because IMAP keeps messages and folders on the server, so every device sees the same mailbox. A is used to send mail, not to retrieve or synchronize a mailbox. B queries directory services such as user accounts and does not retrieve email. C normally downloads messages to one device and removes them from the server, so devices fall out of sync.

Networking

Sample question 7

A user wants an older email client to download messages to the computer and delete them from the mail server. Which port does the protocol for this behavior use by default?

  1. 25
  2. 110
  3. 143
  4. 445
Show correct answer and explanation

Correct answer: B. 110

B is correct because POP3 downloads mail to the client and, by default, removes it from the server; it uses TCP port 110. A is used by SMTP to send email, not to download it. C is used by IMAP, which keeps messages on the server rather than removing them. D is used by SMB for file and printer sharing.

Networking

Sample question 8

A firewall sits between client computers and the DHCP server that leases their addresses. Which ports must the firewall allow for DHCP to work?

  1. 20 and 21
  2. 67 and 68
  3. 137 and 139
  4. 161 and 162
Show correct answer and explanation

Correct answer: B. 67 and 68

B is correct because DHCP servers listen on UDP port 67 and DHCP clients use UDP port 68. A are used by FTP for data transfer and control connections. C are part of the NetBIOS/NetBT range used by legacy Windows networking. D are used by SNMP for device monitoring and traps, not by DHCP.

Networking

Sample question 9

A help desk application must look up user accounts and group memberships in a company's directory service. Which port does the unencrypted directory query protocol use by default?

  1. 143
  2. 389
  3. 445
  4. 3389
Show correct answer and explanation

Correct answer: B. 389

B is correct because LDAP, the protocol used to query directory services such as Active Directory, uses port 389. A is used by IMAP to access email on a mail server. C is used by SMB for Windows file and printer sharing. D is used by RDP for remote desktop sessions.

Networking

Sample question 10

A user maps a network drive to a shared folder on a Windows file server. Which port does the file sharing protocol use?

  1. 21
  2. 389
  3. 443
  4. 445
Show correct answer and explanation

Correct answer: D. 445

D is correct because SMB/CIFS, the protocol Windows uses for file and printer sharing, runs directly over TCP port 445. A is used by FTP for control commands when transferring files. B is used by LDAP to query directory services. C is used by HTTPS for encrypted web traffic.

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