- A
Port 110
Why wrong: Port 110 is for POP3, used to receive email.
- B
Port 143
Why wrong: Port 143 is for IMAP, used to receive email.
- C
Port 587
Port 587 is the standard SMTP submission port, often allowed by ISPs.
- D
Port 993
Why wrong: Port 993 is for IMAPS, secure IMAP for receiving email.
Question 787 of 1,020
220-1201 TCP & UDP Ports Practice Question
This 220-1201 practice question tests your understanding of tcp & udp ports. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that they can receive emails but cannot send any. The email client is configured with SMTP on port 25. The IT team confirms that port 25 is blocked by the ISP. Which alternative port should be used for SMTP submission?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Port 587
Port 587 is the standard SMTP submission port defined in RFC 6409 for email clients to send outgoing mail. Unlike port 25, which is used for SMTP relay between mail servers and is often blocked by ISPs to prevent spam, port 587 is specifically designated for client-to-server submission and typically supports STARTTLS encryption. Using port 587 bypasses the ISP's block on port 25 while adhering to modern email security practices.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Port 110
Why it's wrong here
Port 110 is for POP3, used to receive email.
- ✗
Port 143
Why it's wrong here
Port 143 is for IMAP, used to receive email.
- ✓
Port 587
Why this is correct
Port 587 is the standard SMTP submission port, often allowed by ISPs.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Port 993
Why it's wrong here
Port 993 is for IMAPS, secure IMAP for receiving email.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that any port associated with email (like POP3 on 110 or IMAP on 143) can be used for sending, when in fact only SMTP-specific ports (25, 587, or 465) handle outgoing mail.
Detailed technical explanation
How to think about this question
SMTP traditionally used port 25 for both server-to-server relay and client submission, but ISPs often block port 25 to curb spam from compromised home devices. Port 587 (submission) was standardized in RFC 4409 (updated by RFC 6409) to separate client submission from server relay, and it typically requires authentication (AUTH) and encryption via STARTTLS. In practice, many email providers also support port 465 for SMTP over SSL, but port 587 is the official IANA-registered submission port and the most common alternative when port 25 is blocked.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
TCP & UDP Ports — This question tests TCP & UDP Ports — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Port 587 — Port 587 is the standard SMTP submission port defined in RFC 6409 for email clients to send outgoing mail. Unlike port 25, which is used for SMTP relay between mail servers and is often blocked by ISPs to prevent spam, port 587 is specifically designated for client-to-server submission and typically supports STARTTLS encryption. Using port 587 bypasses the ISP's block on port 25 while adhering to modern email security practices.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.
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