.well-known/traffic-advice - Chrome Privacy Preserving Prefetch Proxy
Do I need to worry about .well-known/traffic-advice not being found on my server?
If you have seen an entry in your website logs for:
.well-known/traffic-advice
you may have wondered what it was
all about and if you should be concerned.
If you are a small website owner and you don't have a high volume of traffic and you see this error in
your server logs then you do not need to worry.
If you need your pages to be loaded quickly and you are concerned with suppressing all 404 errors from
you logs (not a bad thing to do), again, you don't need to worry as you can place an empty directory for
the search engine bot to find.
What the log entry means:
.well-known/traffic-advice is a directory that you can create on your server
so that it can be found by Google when their search engine spider looks of it.
It can be seen in server log entries with requests for:
It would seem that the .well-known/traffic-advice log entry is one that is generated by a process
called "Chrome Privacy Preserving Prefetch Proxy".
Top
From what I can gather this is an initiative by Google to speed the rendering of webpages.
If the directory .well-known and the file traffic-advice does not exist it will generate a 404, file not found.
The operation of Chrome Privacy Preserving Prefetch Proxy is being studied further.
Chrome Privacy Preserving Prefetch Proxy
I can create the directory on the server but at the moment I am not sure what to place in it. (Done)
See what turns up in server logs.
StackExchange
A description of how the prefetch process works can be found on the StackExchange website
"
Googlebot with name "Chrome Privacy Preserving Prefetch Proxy" tries to find instructions if it can preload your
website for the user surfing on Chrome
(Chrome thinks, for example, the link to your website is going to be clicked on).
"
"
Basically what we, webmasters, are interested in is to get rid of 404s caused by this feature. The most simplest
way is to create the file traffic-advice (without any extension) in the directory .well-known with the content:
"
What developer.chrome.com say:
"
How Private Prefetch Proxy works
Secure communication channel
This feature uses a CONNECT proxy to establish a secure communication channel between Chrome and the server hosting the
content to be prefetched.
This secure communication channel prevents the proxy from inspecting any data transfer. Notably, while Private Prefetch
Proxy necessarily sees the host name in order to establish a secure communication channel, it does not see the full URLs,
nor the resources themselves.
"
Advice for website owners
Again from Google Chrome Developers.
"
There is no action required from website owners to start benefiting from private prefetch proxy on links for
which the
user has no cookies or local state. From our experiments, this is a significant opportunity for most websites.
Besides, it's always a good idea to impress first-time visitors or infrequent visitors with a super fast
loading experience.
From past experiments, we’ve seen between 20% to 30% faster Largest Contentful Paint on prefetched
navigations.
"
Further thoughts on .well-known/traffic-advice
Apart from what I can determine from the discussion on StackExchange it is not clear what a webmaster
can do to take advantage
of Private Prefetch Proxy.
The information:
"How Private Prefetch Proxy works" comes from the developer.chrome.com
as such any changes will only apply to Chrome browsers.
"
The way that cached data is handled and how pages are rendered after changes have been made to those pages
will have an impact on what your visitors find when they make a search.
"
Largest Contentful Paint (LCP) - web.dev says:
"
Historically, it's been a challenge for web developers to measure how quickly the main content of a web page
loads and is visible to users.
Older metrics like load or DOMContentLoaded are not good because they don't necessarily correspond to what
the user sees on their screen. And newer, user-centric performance metrics like First Contentful Paint
(FCP) only capture the very beginning of the loading experience. If a page shows a splash screen
or displays a loading indicator, this moment is not very relevant to the user.
The Largest Contentful Paint (LCP) metric reports the render time of the largest image or text block visible
within the viewport, relative to when the page first started loading.
"
Semrush - says:
"
Largest Contentful Paint (LCP) is a user experience (UX) metric. It’s the time it takes between the
browser starting to load a page and the largest content element (image or text block) on that page appearing
on the screen.
LCP is one of the Core Web Vitals, a set of three metrics Google uses to measure a website’s performance in
the context of UX. The other two are:
First Input Delay (FID): how much time it takes the page to respond when a user attempts to interact with it
Cumulative Layout Shift (CLS): a measure of how much the page layout shifts unexpectedly while the page loads
"
Some other things that seemed to be searched for:
- resource-that-should-not-exist-whose-status-code-should-not-be-200/ - reason for not returning
status code 200
- security.txt
- apple-app-site-association
- change-password
- eassetlinks.json
