MX record priority increases as the number increases. (True/False.)

The statement is incorrect. In the Domain Name System (DNS), the priority for a Mail Exchanger (MX) record is determined by a preference number, where a lower numerical value indicates a higher priority. When a mail transfer agent (MTA) looks up the MX records for a domain to deliver an email, it will attempt to connect to the mail server with the lowest preference number first. If that server is unavailable, it will then try the server with the next-lowest preference number, and so on.

The statement "MX record priority increases as the number increases" is the direct opposite of how the protocol is defined and implemented. A higher preference number signifies a lower priority and is typically assigned to backup or secondary mail servers that should only be used if the primary servers (with lower numbers) are unreachable.

1. Internet Engineering Task Force (IETF) RFC 5321

"Simple Mail Transfer Protocol"

Section 5.1: This document

which obsoletes the earlier RFC 2821

defines the standard for SMTP. It states

"The MX mechanism provides a way to rank mail servers... A mail server with a lower preference number is said to be 'more preferred' or 'of higher priority'."

2. Internet Engineering Task Force (IETF) RFC 1035

"Domain Names - Implementation and Specification"

Section 3.3.9: This is the foundational document for DNS. In defining the MX record data format

it specifies a 16-bit integer for preference and states: "A 16 bit integer which specifies the preference given to this RR [Resource Record] among others at the same owner. Lower values are preferred."

3. University of California

Berkeley

EECS Courseware

"CS 168

Introduction to the Internet: Architecture and Protocols"

Lecture 16: Naming (DNS): Course materials for foundational networking classes at reputable universities consistently describe this behavior. Lecture notes explain that the MX record includes a preference field

and mailers must try the server with the lowest preference value first. This is a standard and fundamental concept of DNS operation for mail routing.