Survey of Domain Verification Techniques using DNS
draft-sahib-domain-verification-techniques-00
Network Working Group S. Sahib
Internet-Draft S. Huque
Intended status: Informational Salesforce
Expires: 11 September 2021 10 March 2021
Survey of Domain Verification Techniques using DNS
draft-sahib-domain-verification-techniques-00
Abstract
Verification of ownership of domains in the Domain Name System (DNS)
[RFC1034] [RFC1035] often relies on adding or editing DNS records
within the domain. This document lays out the various techniques and
the pros and cons of each.
Discussion Venues
This note is to be removed before publishing as an RFC.
Source for this draft and an issue tracker can be found at
https://github.com/ShivanKaul/draft-sahib-domain-verification-
techniques.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 11 September 2021.
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Table of Contents
1. Introduction
2. Conventions and Definitions
3. Verification Techniques
3.1. TXT based
3.1.1. Examples
3.2. CNAME based
3.2.1. Examples
4. Recommendations
4.1. TXT vs CNAME
4.2. TXT recommendations
4.3. CNAME recommendations
5. Security Considerations
6. IANA Considerations
7. References
7.1. Normative References
7.2. Informative References
Acknowledgments
Authors' Addresses
1. Introduction
Many providers on the internet need users to prove that they control
a particular domain before granting them some sort of privilege
associated with that domain. For instance, certificate authorities
like Let's Encrypt [LETSENCRYPT] ask requesters of TLS certificates
to prove that they operate the domain they're requesting the
certificate for. Providers generally allow for several different
ways of proving domain control, some of which include manipulating
DNS records. This document focuses on DNS techniques for domain
verification; other techniques (such as email or HTML verification)
are out-of-scope.
In practice, DNS-based verification often looks like the provider
generating a random value and asking the requester to create a DNS
record containing this random value and placing it at a location that
the provider can query for. Generally only one temporary DNS record
is sufficient for proving domain ownership.
2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Verification Techniques
3.1. TXT based
Although the original DNS protocol specifications did not associate
any semantics with the DNS TXT record, [RFC1464] describes how to use
them to store attributes in the form of ASCII text key-value pairs
for a particular domain.
host.widgets.com IN TXT "printer=lpr5"
In practice, there is wide variation in the content of DNS TXT
records used for domain verification, and they often do not follow
the key-value pair model.
The same domain name can have multiple distinct TXT records (a TXT
Record Set).
TXT record-based DNS domain verification is usually the default
option for DNS verification. The service provider asks the user to
add a DNS TXT record (perhaps through their domain host or DNS
provider) at the domain with a certain value. Then, the service
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