# RFC 1035: Domain Names — Implementation and Specification

> P. Mockapetris, ISI, November 1987. Establishes the preferred name syntax for domain labels: letters, digits and hyphen, starting with a letter and ending with a letter or digit, a 63-character label limit, and comparison that ignores case. It constrains an identifier only where one is reused as a host name or DNS label, and says nothing about labeling.

Canonical page: https://datacenterlabeling.com/references/s66

Original source: [RFC 1035: Domain Names — Implementation and Specification](https://www.rfc-editor.org/rfc/rfc1035.txt)

## Scope of this source

P. Mockapetris, ISI, November 1987. Establishes the preferred name syntax for domain labels: letters, digits and hyphen, starting with a letter and ending with a letter or digit, a 63-character label limit, and comparison that ignores case. It constrains an identifier only where one is reused as a host name or DNS label, and says nothing about labeling.

Establishes the character set and length limit that apply to a DNS label. It does not establish a labeling requirement.

Rackstamp provides editorial field guidance. IDs, cases, and worksheet entries are fictional examples unless identified otherwise. Distinguish local conventions from adopted standards. Source notes describe the evidence scope; a linked overview is not the full standard or a project approval.

## Related guidance

- [We do not have a naming convention](https://datacenterlabeling.com/problems/naming-convention)