diff --git a/src/net/conf_test.go b/src/net/conf_test.go
new file mode 100644
index 0000000..46e91bc
--- /dev/null
+++ b/src/net/conf_test.go
@@ -0,0 +1,245 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package net
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+type nssHostTest struct {
+	host string
+	want hostLookupOrder
+}
+
+func nssStr(s string) *nssConf { return parseNSSConf(strings.NewReader(s)) }
+
+func TestConfHostLookupOrder(t *testing.T) {
+	tests := []struct {
+		name      string
+		c         *conf
+		goos      string
+		hostTests []nssHostTest
+	}{
+		{
+			name: "force",
+			c: &conf{
+				forceCgoLookupHost: true,
+				nss:                nssStr("foo: bar"),
+			},
+			hostTests: []nssHostTest{
+				{"foo.local", hostLookupCgo},
+				{"google.com", hostLookupCgo},
+			},
+		},
+		{
+			name: "ubuntu_trusty_avahi",
+			c: &conf{
+				nss: nssStr("hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4"),
+			},
+			hostTests: []nssHostTest{
+				{"foo.local", hostLookupCgo},
+				{"foo.local.", hostLookupCgo},
+				{"foo.LOCAL", hostLookupCgo},
+				{"foo.LOCAL.", hostLookupCgo},
+				{"google.com", hostLookupFilesDNS},
+			},
+		},
+		{
+			name: "freebsdlinux_no_resolv_conf",
+			c: &conf{
+				goos: "freebsd",
+				nss:  nssStr("foo: bar"),
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupFilesDNS}},
+		},
+		// On OpenBSD, no resolv.conf means no DNS.
+		{
+			name: "openbsd_no_resolv_conf",
+			c: &conf{
+				goos: "openbsd",
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupFiles}},
+		},
+		{
+			name: "solaris_no_nsswitch",
+			c: &conf{
+				goos: "solaris",
+				nss:  &nssConf{err: os.ErrNotExist},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+		},
+		{
+			name: "openbsd_lookup_bind_file",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"bind", "file"}},
+			},
+			hostTests: []nssHostTest{
+				{"google.com", hostLookupDNSFiles},
+				{"foo.local", hostLookupDNSFiles},
+			},
+		},
+		{
+			name: "openbsd_lookup_file_bind",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"file", "bind"}},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupFilesDNS}},
+		},
+		{
+			name: "openbsd_lookup_bind",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"bind"}},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupDNS}},
+		},
+		{
+			name: "openbsd_lookup_file",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"file"}},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupFiles}},
+		},
+		{
+			name: "openbsd_lookup_yp",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"file", "bind", "yp"}},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+		},
+		{
+			name: "openbsd_lookup_two",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: []string{"file", "foo"}},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+		},
+		{
+			name: "openbsd_lookup_empty",
+			c: &conf{
+				goos:   "openbsd",
+				resolv: &dnsConfig{lookup: nil},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupDNSFiles}},
+		},
+		// glibc lacking an nsswitch.conf, per
+		// http://www.gnu.org/software/libc/manual/html_node/Notes-on-NSS-Configuration-File.html
+		{
+			name: "linux_no_nsswitch.conf",
+			c: &conf{
+				goos: "linux",
+				nss:  &nssConf{err: os.ErrNotExist},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupDNSFiles}},
+		},
+		{
+			name: "files_mdns_dns",
+			c:    &conf{nss: nssStr("hosts: files mdns dns")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupFilesDNS},
+				{"x.local", hostLookupCgo},
+			},
+		},
+		{
+			name: "dns_special_hostnames",
+			c:    &conf{nss: nssStr("hosts: dns")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupDNS},
+				{"x\\.com", hostLookupCgo},     // punt on weird glibc escape
+				{"foo.com%en0", hostLookupCgo}, // and IPv6 zones
+			},
+		},
+		{
+			name: "mdns_allow",
+			c: &conf{
+				nss:          nssStr("hosts: files mdns dns"),
+				hasMDNSAllow: true,
+			},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupCgo},
+				{"x.local", hostLookupCgo},
+			},
+		},
+		{
+			name: "files_dns",
+			c:    &conf{nss: nssStr("hosts: files dns")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupFilesDNS},
+				{"x", hostLookupFilesDNS},
+				{"x.local", hostLookupCgo},
+			},
+		},
+		{
+			name: "dns_files",
+			c:    &conf{nss: nssStr("hosts: dns files")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupDNSFiles},
+				{"x", hostLookupDNSFiles},
+				{"x.local", hostLookupCgo},
+			},
+		},
+		{
+			name: "something_custom",
+			c:    &conf{nss: nssStr("hosts: dns files something_custom")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupCgo},
+			},
+		},
+		{
+			name: "myhostname",
+			c:    &conf{nss: nssStr("hosts: files dns myhostname")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupFilesDNS},
+				{"somehostname", hostLookupCgo},
+			},
+		},
+		{
+			name: "ubuntu14.04.02",
+			c:    &conf{nss: nssStr("hosts: files myhostname mdns4_minimal [NOTFOUND=return] dns mdns4")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupFilesDNS},
+				{"somehostname", hostLookupCgo},
+			},
+		},
+		// Debian Squeeze is just "dns,files", but lists all
+		// the default criteria for dns, but then has a
+		// non-standard but redundant notfound=return for the
+		// files.
+		{
+			name: "debian_squeeze",
+			c:    &conf{nss: nssStr("hosts: dns [success=return notfound=continue unavail=continue tryagain=continue] files [notfound=return]")},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupDNSFiles},
+				{"somehostname", hostLookupDNSFiles},
+			},
+		},
+		{
+			name: "resolv.conf-unknown",
+			c: &conf{
+				nss:    nssStr("foo: bar"),
+				resolv: &dnsConfig{unknownOpt: true},
+			},
+			hostTests: []nssHostTest{{"google.com", hostLookupCgo}},
+		},
+	}
+	for _, tt := range tests {
+		for _, ht := range tt.hostTests {
+			gotOrder := tt.c.hostLookupOrder(ht.host)
+			if gotOrder != ht.want {
+				t.Errorf("%s: useCgoLookupHost(%q) = %v; want %v", tt.name, ht.host, gotOrder, ht.want)
+			}
+		}
+	}
+
+}