.local DNS resolution slow on MacOS

[Jaessun]

Quick summary

There is a known issue with how MacOS resolves the .local domain which can add on average around 3 - 6 seconds to the load time.

This answer on StackOverflow explains it well:

...is most likely the result of Bonjour IPv6 lookups being issued for DNS lookups on .local domains. These IPv6 lookups create a timeout delay until the original IPv4 DNS lookup is issued.

An easy fix would be to add an IPv6 entry to the etc/hosts file in addition to the IPv4 one:

127.0.0.1 my-project.local
::1 my-project.local

As far as I'm aware this is also the same thing that LocalWP does in the etc/hosts file when a new site is created.

Steps to reproduce

1. Create a new site in Studio on MacOS
2. Make sure to use a custom domain name (e.g.: my-project.local)
3. Create a second site
4. This time, make sure not to use a custom domain name
5. Run the following command in a terminal to measure the time it takes to get a response from the first site:
   time curl -I http://my-project.local/ > /dev/null (replace my-project.local with whatever domain name you chose at step 2)
6. Run the following command in a terminal to measure the time it takes to get a response from the second site:
   time curl -I http://localhost:8882/ > /dev/null (replace 8882 with the actual port of your second site)
7. Compare the results

I have also tried the proposed fix by editing my etc/hosts file to add the IPv6 entry. For me, this has reduced the time for the curl command from 5.6s to 0.6s.

What you expected to happen

The DNS resolution should be fast.

What actually happened

The DNS resolution was slow.

Impact

Some (< 50%)

Available workarounds?

Yes, easy to implement

Platform

Mac Silicon

Logs or notes

No response

[youknowriad]

I tried to reproduce this locally but couldn't, I'm on MacOS and I have IPv6 enabled. Do you know why this could be the case?

[Jaessun]

I've tried the same test on my colleague's Mac and got the same result as mine. However we are both currently on MacOS Sequoia 15.5, so one major version behind. So maybe this is a difference between versions of MacOS? Can you share which version of MacOS are you working with?

I will try to update my OS in the coming days to test if the same issue happens on MacOS Tahoe and I'll be back with the result 🙂

[linear]

from @youknowriad:

I'm on MacOS 26.5.1 Tahoe

[wojtekn]

@Jaessun, did you have a chance to test it after the OS update?

[Jaessun]

Yep, my system was updated yesterday, so I've just done the test again and unfortunately the result is exactly the same: about 5s for the curl request to complete, unless I map ::1 to my .local domain in my hosts file, in which case the curl request completes pretty much instantaneously.