Mozilla DNS Over HTTPS Enabled Default US?

In the United States, Mozilla has not enabled DNS over HTTPS (DoH) by default for all Firefox users. As of 2025, DoH remains an opt-in feature in the U.S.; users must manually enable it in Firefox settings, whereas in some other regions (like Russia and Ukraine) Mozilla has turned it on by default due to specific network conditions.

Background: What Is DNS Over HTTPS?

DNS (Domain Name System) is the internet’s phonebook. When you type a website address, your device sends a DNS query to a resolver (usually your internet service provider) to find the corresponding IP address. Traditionally, these queries are sent in plain text, meaning anyone on the network—your ISP, a Wi-Fi eavesdropper, or a malicious actor—can see which domains you visit.

DNS over HTTPS (DoH) encrypts these queries and sends them through a secure HTTPS connection to a DoH-compatible resolver, such as Cloudflare or NextDNS. This prevents third parties from reading your DNS traffic. Mozilla began testing DoH in Firefox in 2018 and rolled it out as an opt-in feature in the U.S. in 2020, but it was never enabled by default in the U.S. due to concerns about centralization, privacy trade-offs, and potential conflicts with enterprise network policies.

How DoH Works in Firefox

When DoH is enabled in Firefox, the browser bypasses the system’s default DNS resolver and sends encrypted queries to a designated DoH provider. Firefox uses a secure connection to the provider’s server, which then resolves the domain and returns the IP address. The browser also has a fallback mechanism: if the DoH query fails, it will use the system’s regular DNS to avoid breaking internet access.

Firefox’s implementation includes a feature called “automatic mode,” where the browser decides whether to use DoH based on whether the system’s current DNS provider appears to be a privacy threat. However, in the U.S., this automatic mode is not the default; users must choose to enable it.

How to Enable or Disable DoH in Firefox

If you want to control DoH in Firefox, follow these steps:

1. Open Firefox and click the menu button (three horizontal lines) in the top-right corner.
2. Select Settings (or Options on some systems).
3. In the left sidebar, click Privacy & Security.
4. Scroll down to the DNS over HTTPS section.
5. Choose one of the following:
   • Off – DoH is completely disabled; Firefox uses the system’s DNS.
   • Default protection – Firefox uses DoH only if it detects that your current DNS provider might be insecure (this is the default in some regions, but not in the U.S.).
   • Increased protection – Firefox always uses DoH and will fall back to the system DNS only if the DoH query fails.
6. If you choose increased protection, you can also select a custom DoH provider from the drop-down list or enter a custom URL.

Note that the exact wording of these options may vary slightly between Firefox versions, but the general process remains the same.

Common Misconceptions About DoH

One common misconception is that DoH makes you completely anonymous. It does not—it only encrypts DNS queries. Your IP address is still visible to the websites you visit, and the DoH provider can see all your DNS queries (unless you use a provider with a strict no-logging policy). Another misconception is that DoH is the same as a VPN. A VPN encrypts all traffic, not just DNS, and routes it through a server, whereas DoH only encrypts DNS queries.

Another misconception is that DoH is always faster. In some cases, it can be slower because the DNS query has to travel to a different server, but in other cases, it can be faster if your ISP’s DNS is slow. Performance varies by network and provider.

Potential Issues and How to Fix Them

Enabling DoH can cause problems in certain environments:

• Corporate networks: Many companies use DNS for content filtering or security monitoring. DoH bypasses these controls, so IT departments may block DoH traffic. If you experience issues on a work network, disable DoH or use the “Default protection” mode.
• Parental controls: Similar to corporate networks, home parental-control systems that rely on DNS filtering may not work with DoH. You may need to disable DoH for those controls to function.
• Captive portals: Some public Wi-Fi networks use a captive portal (a login page) that requires DNS to redirect you. DoH can interfere with this. If you can’t connect to a public Wi-Fi, try disabling DoH temporarily.
• Slow browsing: If DoH queries are slow, try switching to a different DoH provider. Cloudflare and NextDNS are popular options, but you can also use your own server if you have one.

If you encounter any of these issues, you can quickly disable DoH by going back to the DNS over HTTPS settings and selecting “Off.”

Comparing DoH to Other DNS Encryption Methods

DoH is not the only way to encrypt DNS queries. DNS over TLS (DoT) is another method that uses a dedicated port (853) for encrypted DNS, but it is not as easily integrated into browsers because it requires system-level configuration. DNSCrypt is another protocol that encrypts DNS traffic but is less widely supported.

DoH’s advantage is that it uses the standard HTTPS port (443), which makes it harder to block—firewalls that allow web traffic will also allow DoH. This is why it’s often preferred by privacy advocates. However, this same feature can be a problem for network administrators who want to enforce DNS policies.

Frequently Asked Questions

Is DNS over HTTPS safe?

Yes, DoH is generally safe. It encrypts your DNS queries, preventing eavesdroppers from seeing which domains you visit. However, you should choose a reputable DoH provider that has a clear privacy policy. Also, DoH does not protect you from other tracking methods, such as cookies or fingerprinting.

Does DoH slow down my internet?

It can, but not always. The speed depends on the DoH provider’s server location and your network. In some cases, DoH may be faster than your ISP’s DNS, especially if your ISP’s DNS is slow. You can test by comparing browsing speeds with DoH on and off.

Can I use DoH with other browsers?

Yes, most modern browsers support DoH. Chrome, Edge, and Brave have built-in DoH options. However, the default settings vary by browser and region. For example, Chrome uses the system’s DNS by default, but you can enable DoH in its settings.

Will DoH hide my browsing history from my ISP?

DoH hides your DNS queries from your ISP, but your ISP can still see the IP addresses you connect to, which often reveals the websites you visit. To hide your browsing history from your ISP, you would need a VPN or Tor, which encrypts all traffic.

Why did Mozilla not enable DoH by default in the US?

Mozilla faced significant backlash from ISPs and some policymakers who argued that DoH would bypass parental controls and network security. There were also concerns about centralizing DNS queries with a single provider. As a result, Mozilla decided to make DoH opt-in in the U.S., while still promoting it as a privacy feature.

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