diff --git a/src/appdb.js b/src/appdb.js
index 03f157a55..b1fe63600 100644
--- a/src/appdb.js
+++ b/src/appdb.js
@@ -27,6 +27,8 @@ exports = module.exports = {
     setOwner: setOwner,
     transferOwnership: transferOwnership,
 
+    setSubdomainDnsRecordId: setSubdomainDnsRecordId,
+
     // installation codes (keep in sync in UI)
     ISTATE_PENDING_INSTALL: 'pending_install', // installs and fresh reinstalls
     ISTATE_PENDING_CLONE: 'pending_clone', // clone
@@ -623,3 +625,17 @@ function transferOwnership(oldOwnerId, newOwnerId, callback) {
         callback(null);
     });
 }
+
+function setSubdomainDnsRecordId(domain, subdomain, dnsRecordId, callback) {
+    assert.strictEqual(typeof domain, 'string');
+    assert.strictEqual(typeof subdomain, 'string');
+    assert.strictEqual(typeof dnsRecordId, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    database.query('UPDATE subdomains SET dnsRecordId = ? WHERE domain = ? AND subdomain = ?', [ dnsRecordId, domain, subdomain ], function (error, results) {
+        if (error && error.code === 'ER_NO_REFERENCED_ROW_2') return callback(new DatabaseError(DatabaseError.NOT_FOUND, 'No such subdomain'));
+        if (error) return callback(new DatabaseError(DatabaseError.INTERNAL_ERROR, error));
+
+        callback(null);
+    });
+}
diff --git a/src/apptask.js b/src/apptask.js
index 8b86c4242..4429b5938 100644
--- a/src/apptask.js
+++ b/src/apptask.js
@@ -343,10 +343,8 @@ function registerAlternateDomains(app, overwrite, callback) {
             }, function (error, result) {
                 if (error || result instanceof Error) return callback(error || result);
 
-                // TODO we need to stash this into the subdomains table instead of apps table
                 // dnsRecordId tracks whether we created this DNS record so that we can unregister later
-                // updateApp(app, { dnsRecordId: result }, callback);
-                callback();
+                appdb.setSubdomainDnsRecordId(domain.domain, domain.subdomain, result, callback);
             });
         }, callback);
     });