diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 77ed77918c..abd0abbf9b 100644
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -2676,9 +2676,9 @@ Token=prefixstable:2002:da8:1::</programlisting></para>
       <varlistentry>
         <term><varname>DNSLifetimeSec=</varname></term>
 
-        <listitem><para>Lifetime in seconds for the DNS server addresses listed
-        in <varname>DNS=</varname> and search domains listed in
-        <varname>Domains=</varname>.</para></listitem>
+        <listitem><para>Lifetime in seconds for the DNS server addresses listed in
+        <varname>DNS=</varname> and search domains listed in <varname>Domains=</varname>. Defaults to
+        604800 seconds (one week).</para></listitem>
       </varlistentry>
 
     </variablelist>
diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
index afbb9d61db..c3b408c4e9 100644
--- a/src/network/networkd-network.c
+++ b/src/network/networkd-network.c
@@ -420,6 +420,7 @@ int network_load_one(Manager *manager, OrderedHashmap **networks, const char *fi
                 .dhcp_server_emit_timezone = true,
 
                 .router_lifetime_usec = 30 * USEC_PER_MINUTE,
+                .router_dns_lifetime_usec = 7 * USEC_PER_DAY,
                 .router_emit_dns = true,
                 .router_emit_domains = true,