diff --git a/gnu/services/networking.scm b/gnu/services/networking.scm
index 77841a18d4..5bb8638930 100644
--- a/gnu/services/networking.scm
+++ b/gnu/services/networking.scm
@@ -427,6 +427,8 @@ (define %ntp-servers
   ;; Default set of NTP servers. These URLs are managed by the NTP Pool project.
   ;; Within Guix, Leo Famulari <leo@famulari.name> is the administrative contact
   ;; for this NTP pool "zone".
+  ;; The full list of available URLs are 0.guix.pool.ntp.org,
+  ;; 1.guix.pool.ntp.org, 2.guix.pool.ntp.org, and 3.guix.pool.ntp.org.
   (list
    (ntp-server
     (type 'pool)