diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 5601485555..0a187e256a 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -993,10 +993,14 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
your machine supports IPv6, you can also use those addresses.
TCP/IP communication is
always used when a nonempty string is specified for this parameter.
+ If this parameter is not specified, the value of host
+ will be looked up to find the corresponding IP address — or, if
+ host specifies an IP address, that value will be
+ used directly.
- Using hostaddr instead of host allows the
+ Using hostaddr allows the
application to avoid a host name look-up, which might be important
in applications with time constraints. However, a host name is
required for GSSAPI or SSPI authentication