diff --git a/dnf.spec b/dnf.spec
index c70f923..c691c26 100644
--- a/dnf.spec
+++ b/dnf.spec
@@ -193,6 +193,7 @@ Requires:       python2-enum34
 Requires:       %{name}-data = %{version}-%{release}
 %if 0%{?fedora}
 Recommends:     deltarpm
+# required for DNSSEC main.gpgkey_dns_verification https://dnf.readthedocs.io/en/latest/conf_ref.html
 Recommends:     python2-unbound
 %endif
 Requires:       python2-hawkey >= %{hawkey_version}
@@ -238,6 +239,7 @@ Requires:       python3-libcomps >= %{libcomps_version}
 Requires:       python3-libdnf
 BuildRequires:  python3-rpm >= %{rpm_version}
 Requires:       python3-rpm >= %{rpm_version}
+# required for DNSSEC main.gpgkey_dns_verification https://dnf.readthedocs.io/en/latest/conf_ref.html
 Recommends:     python3-unbound
 %if 0%{?rhel} && 0%{?rhel} <= 7
 Requires:       rpm-plugin-systemd-inhibit