Core networking
app-site-association.cdn-apple.com
app-site-association.cdn-apple.com and app-site-association.networking.apple serve Associated Domains. Apple says that these underpin universal links in macOS Big Sur and later.
Short answer
Apple's hosts for Associated Domains, which universal links and other app-to-website links rely on.
Block with care
Blocking them can stop links from opening in their apps, and other features built on Associated Domains.
- Matches
app-site-association.cdn-apple.comapp-site-association.networking.apple
A name with *. covers every name under it: *.push.apple.com matches 1-courier.push.apple.com.
What it serves
Apple's enterprise host list names both in its Associated Domains section, for “Associated domains for universal links”, on iOS, iPadOS, macOS and visionOS.
Apple says that universal links let an app present content in place of all or part of a website.
Apple doesn't say which process on the Mac fetches the association data.
What breaks if you block it
Block with care
Blocking them can stop links from opening in their apps, and other features built on Associated Domains.
What breaks if you block it
- Universal links may open in the browser instead of the app.
- Other features built on Associated Domains may fail.
With Kilobat Pro and the network filter, you can block a host for every app or for one app: in Connections, select a connection and choose Block. Apple’s own services are never blocked by Kilobat’s Protection lists.
Apple’s rules for its hosts
Apple’s list, Use Apple products on enterprise networks, says that devices open these connections, not Apple’s servers. Apple services fail any connection that uses HTTPS interception, so a proxy that inspects TLS should leave Apple’s hosts alone.
If a firewall allows hosts by name, allowing *.apple.com covers most Apple services, Apple says. A firewall that works only with addresses can allow 17.0.0.0/8 for IPv4, and 2403:300::/32, 2620:149::/32 and 2a01:b740::/32 for IPv6.
To see which app on your Mac opened a connection to this host, use Kilobat’s Connections tab, or the agent network log for AI agents.
Sources
Checked on 1 November 2026.