Fix/dns initialization (#954)

The systemd HostManagers require valid, initialized network interface

client/internal/dns/server_test.go

@@ -225,6 +225,10 @@ func TestUpdateDNSServer(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
+			err = dnsServer.Initialize()
+			if err != nil {
+				t.Fatal(err)
+			}
 			defer func() {
 				err = dnsServer.hostManager.restoreHostDNS()
 				if err != nil {
@@ -291,7 +295,7 @@ func TestDNSServerStartStop(t *testing.T) {
 			dnsServer := getDefaultServerWithNoHostManager(t, testCase.addrPort)
 
 			dnsServer.hostManager = newNoopHostMocker()
-			dnsServer.Start()
+			dnsServer.listen()
 			time.Sleep(100 * time.Millisecond)
 			if !dnsServer.listenerIsRunning {
 				t.Fatal("dns server listener is not running")