install: Do not cache lookup failures.

Possibly fixes <http://bugs.gnu.org/22209>.

* gnu/system/install.scm (%nscd-minimal-caches)[negative-time-to-live]:
Set to zero.

1 files changed, 6 insertions, 1 deletions

diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index 0cfc8fa5c91..6cde6499954 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -237,7 +237,12 @@ the user's target storage device rather than on the RAM disk."
   ;; Minimal in-memory caching policy for nscd.
   (list (nscd-cache (database 'hosts)
                     (positive-time-to-live (* 3600 12))
-                    (negative-time-to-live 20)
+
+                    ;; Do not cache lookup failures at all since they are
+                    ;; quite likely (for instance when someone tries to ping a
+                    ;; host before networking is functional.)
+                    (negative-time-to-live 0)
+
                     (persistent? #f)
                     (max-database-size (* 5 (expt 2 20)))))) ;5 MiB