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Fact Check: Is FQDN case sensitive?

Fact Check: Is FQDN case sensitive?

Published May 25, 2025
ByFactChecker 1.1 avatarFactChecker 1.1
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Mostly True

# Is FQDN Case Sensitive? ## Introduction The claim in question is whether Fully Qualified Domain Names (FQDNs) are case sensitive. This topic is rel...

Is FQDN Case Sensitive?

Introduction

The claim in question is whether Fully Qualified Domain Names (FQDNs) are case sensitive. This topic is relevant for web developers, IT professionals, and anyone involved in domain registration and management. The assertion that FQDNs are case insensitive is prevalent, but there are nuances that merit further exploration.

What We Know

  1. Definition of FQDN: A Fully Qualified Domain Name specifies the exact location of a resource in the Domain Name System (DNS). It includes the hostname and the domain name, creating a unique identifier for a resource on the internet 14.

  2. Case Sensitivity: According to several sources, including RFC 4343, domain names, including FQDNs, are generally considered case-insensitive. This means that "Example.com" and "example.com" are treated as equivalent in the context of DNS 1568.

  3. Exceptions and Specific Cases: While the DNS itself is case-insensitive, certain applications or systems may treat hostnames differently. For example, some internal systems may have case-sensitive configurations, leading to discrepancies in how FQDNs are resolved 310.

  4. Input and Output Case Preservation: RFC 4343 clarifies that while ASCII label comparisons are case insensitive, the case must be preserved on output. This means that while the DNS treats the names as equivalent, the output may reflect the original case used in the query 5.

Analysis

The reliability of the sources varies, and it is essential to evaluate them critically:

  • RFC 4343 is a formal document from the Internet Engineering Task Force (IETF) and is considered a highly credible source. It provides a technical foundation for understanding case sensitivity in DNS 5.

  • Domainmarkia and The Hosting Finder provide straightforward explanations that align with the consensus on case insensitivity in DNS. However, they are less formal than RFCs and may not delve deeply into technical specifics, which could limit their authority 26.

  • Server Fault presents a real-world scenario where case sensitivity issues arose in an internal domain setup. This highlights that while DNS is generally case insensitive, specific implementations may vary, suggesting that context matters 3.

  • GoDaddy and Spiceworks offer user-friendly explanations but may cater to a broader audience, which could lead to oversimplifications. Their credibility is moderate, as they are well-known in the domain registration and IT support sectors, but they may have commercial interests that could influence their presentation of information 78.

  • Abhijit Rawool's article discusses the nuances of case sensitivity in URLs, indicating that while domain names are case insensitive, other components of URLs may not be. This adds complexity to the discussion and emphasizes the need for careful consideration in web development 9.

Conclusion

Verdict: Mostly True

The claim that Fully Qualified Domain Names (FQDNs) are case insensitive is mostly true based on the consensus from credible sources, particularly RFC 4343, which states that domain names are treated as equivalent regardless of case in the context of DNS. However, there are important nuances to consider. While the DNS itself is case insensitive, specific applications or systems may implement case sensitivity differently, leading to potential discrepancies in how FQDNs are resolved.

It is crucial to acknowledge that while the general rule holds, exceptions exist, particularly in internal systems or specific configurations. This complexity means that users should remain cautious and consider the context in which FQDNs are being used.

The evidence available does not provide a definitive answer applicable to all scenarios, highlighting the limitations in our understanding of case sensitivity across different systems. Readers are encouraged to critically evaluate information and consider the specific context of their use cases when dealing with FQDNs.

Sources

  1. Fact Check: Are Fully Qualified Domain Names (FQDNs) case-sensitive? - Truth or Fake
  2. Are Domain Names Case Sensitive? (+ Your Questions Answered) - Domainmarkia
  3. Is the hostname case sensitive? - Server Fault
  4. Understanding FQDN with Examples - How to Use Linux
  5. RFC 4343 - Domain Name System (DNS) Case Insensitivity Clarification - IETF
  6. Are Domain Names Case Sensitive | The Hosting Finder - The Hosting Finder
  7. What's a Fully Qualified Domain Name (FQDN) and what's it ... - GoDaddy
  8. FQDN Meaning, Elements, Importance, and Examples - Spiceworks
  9. Is DNS Case-Sensitive? (There's More To It Than Just Case Sensitivity) - Abhijit Rawool
  10. FQDN Resolution Issues by Case-Sensitive FQDN Name - F5

In summary, the case sensitivity of FQDNs is generally considered to be non-existent within the DNS, but specific implementations may vary, and further investigation into individual systems may be required for a complete understanding.

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Uh so in that opinion in 2005 from OLC they said essentially that an autopin could be used by a subordinate but the president's determination as to sign the document can never be delegated. Can that authority 02:41 be transferred to a staff or a machine without the president's explicit authorization? Never. And if you look at the statistics, the statistics are stunning. In 2021, President Biden issued 78 executive orders. None were signed with an auto pen. That first year the presidency, Biden I suppose was relatively lucid and 78 executive orders he signed by hand. The second year, however, we see the auto pen emerged. 03:15 The first auto pen executive order was issued on 15th 2022. After that day 100% of the executive orders issued in 2022 were signed by an autopen. In 2023 Biden issued twenty-four executive orders. 16 were auto penned. In 20twenty-four Biden issued 19. 14 were auto penned. In twenty twenty-5 Biden issued fourteen executive orders every single one was auto pins. 03:52 Mister Wald let me ask you as a legal matter if there's a law that's passed both houses of Congress and it goes to the White House and a staffer autopins signing that law without the president's authorization is that law legally passed and signed in the law? No. If an executive order is issued and a staffer autopins it without the president's authorization, is that executive order legally binding? No. And if a pardon issued from the President of 04:22 the United States and a staffer auto pens it without the president's authorization. Is that pardon legally binding? No. Under the Biden White House the ceremonial song hailed to the chief was effectively replaced with hail to the pen and it was an outright assault on democracy and every reporter covering this ought to ask why doesn't a Democrat care? We heard about the moral responsibilities of a staffer. 04:54 How about an elected senator who knows damn well that if we get into a war and Iran is preparing to fire a nuclear weapon at the United States that the commander in chief is busy playing with his jello and he's not competent to defend ourselves and every member of the cabinet, the chief of staff, the press secretary, and the members of Congress who lied about this on a daily basis with the press's complicity. They are all responsible for subverting democracy. Angry Ted Cruz is perhaps my favorite version of 05:27 Ted Cruz because when he's getting history on it, you might want to take a listen. He is definitely angry that there's some acting going on here in the line of hail to the chief change from hail to the pen that's not a smart line but it's still the truth. The truth is in this video right here ladies and gentlemen. The change in the way Joe Biden used the autopin is a steady upward moving graph from twenty twenty-one to the end of his presidency in early twenty 05:58 twenty-five. Okay? That is a noticeable issue. And if he does not directly authorize the autopin we've got We've got grounds to go through every single law Joe Biden has signed that way and perhaps ignore them all together. There's way more evidence behind the autopin theory and hopefully it ends up sticking. I I hope it does because I think this is in a way worse than the Bill Clinton perjury case. Cuz Bill 06:28 Clinton basically lied before Congress lied directly to the American people lied under oath. This is worse in a way. Because lying under oath means that you know where the truth is and you're just hoping to get away with it and there's a direct law. This however Signing with the auto pin is more opaque. It is an ultimate he said she said and you're dont rate the opinion oo just fact if there is

Detailed fact-check analysis of: Transcript 00:00 For all of their strutting about protesting that they support democracy. Not a one of them gave a damn about democracy when they pulled Biden off the ballot and dropped Kamala Harris in without a single Democrat primary voter voting for him. And you know what? Not a single Democrat is here today because not a single one of them gives a damn about the fact that they lied to the American people for four years. They knew Every one of them knew that Joe Biden was 00:34 mentally not competent to do the job. The White House Press Secretary. She knew when she stood in front of the American people and lied over and over and over again and they're not here because they can't defend themselves. It wasn't a surprise for four years the White House hid President Biden from Republican Senators. Would not let him meet with us. He served 40 years in this body. We all know him. And they deliberately lied and by the way Jake Tapper had a bombshell 01:08 book exposing the incredible scandal that Biden's mental decline was covered up by Jake Tapper. There's a Yiddish word and that truly is how dare we lie and cover up what we all knew. Now I have been asked literally a thousand times by Texans. Was running the country? And I'm going to give 01:40 you the most terrifying answer. I don't know. I genuinely don't know. And not a single Democrat here cares. The most telling proof of Biden's decline came with the signature of the president. The symbol of executive authority that was outsourced to a machine. Mister Wald you're a lawyer who served in the White House Council's Office. You understand the gravity of presidential action. Does the president's signature 02:10 carry legal and constitutional weight under article two? Yes. Is the act of signing an executive order or signing a law or granting a pardon a delegable duty of the president. Uh so in that opinion in 2005 from OLC they said essentially that an autopin could be used by a subordinate but the president's determination as to sign the document can never be delegated. Can that authority 02:41 be transferred to a staff or a machine without the president's explicit authorization? Never. And if you look at the statistics, the statistics are stunning. In 2021, President Biden issued 78 executive orders. None were signed with an auto pen. That first year the presidency, Biden I suppose was relatively lucid and 78 executive orders he signed by hand. The second year, however, we see the auto pen emerged. 03:15 The first auto pen executive order was issued on 15th 2022. After that day 100% of the executive orders issued in 2022 were signed by an autopen. In 2023 Biden issued twenty-four executive orders. 16 were auto penned. In 20twenty-four Biden issued 19. 14 were auto penned. In twenty twenty-5 Biden issued fourteen executive orders every single one was auto pins. 03:52 Mister Wald let me ask you as a legal matter if there's a law that's passed both houses of Congress and it goes to the White House and a staffer autopins signing that law without the president's authorization is that law legally passed and signed in the law? No. If an executive order is issued and a staffer autopins it without the president's authorization, is that executive order legally binding? No. And if a pardon issued from the President of 04:22 the United States and a staffer auto pens it without the president's authorization. Is that pardon legally binding? No. Under the Biden White House the ceremonial song hailed to the chief was effectively replaced with hail to the pen and it was an outright assault on democracy and every reporter covering this ought to ask why doesn't a Democrat care? 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