diff --git a/client.conf.sample b/client.conf.sample
index 7e31b04..9dc8605 100644
--- a/client.conf.sample
+++ b/client.conf.sample
@@ -7,4 +7,19 @@
 ;   nrd-0.1
 ;   ndnd-tlv-0.7
 ;   ndnx-0.7
-protocol=nrd-0.1
\ No newline at end of file
+protocol=nrd-0.1
+
+; "pib" determines which Public Info Base (PIB) should used by default in applications.
+; If "pib" is not specified, the default PIB will be used.
+; Note that default PIB could be different on different system.
+; If "pib" is specified, it may have a value of:
+;   sqlite3
+; pib=sqlite3
+
+; "tpm" determines which Trusted Platform Module (TPM) should used by default in applications.
+; If "tpm" is not specified, the default TPM will be used.
+; Note that default TPM could be different on different system.
+; If "tpm" is specified, it may have a value of:
+;   file
+;   osx-keychain
+; tpm=file
\ No newline at end of file