diff --git a/app/methods/site_domain_methods.py b/app/methods/site_domain_methods.py
index 2cc4541..60e3f8e 100644
--- a/app/methods/site_domain_methods.py
+++ b/app/methods/site_domain_methods.py
@@ -147,8 +147,9 @@ def get_site_domain_rec_list(
 # ### BEGIN ### API Site Domain Methods ### lookup_site_domain_fqdn() ###
 def lookup_site_domain_fqdn(
         fqdn: str,
-        # TODO: Accept access_key as an argument for validation (str|None)
-        # access_key: Optional[str] = None,
+    # Accept access_key as an argument for validation (str|None)
+    access_key: Optional[str] = None,
+    referrer: Optional[str] = None,
         enabled: str = 'enabled', # enabled, disabled, all
         limit: int = 100,
         offset: int = 0,
@@ -158,22 +159,37 @@ def lookup_site_domain_fqdn(
 
     data = {}
     data['fqdn'] = fqdn
-    # TODO: If access_key is provided, add it to the data dict for SQL parameterization
-    # if access_key is not None:
-    #     data['access_key'] = access_key
+    # If access_key is provided, add it to the data dict for SQL parameterization
+    data['domain_access_key'] = access_key
+    if referrer:
+        data['required_referrer'] = referrer
 
     sql_enabled, data['enable'] = sql_enable_part(table_name='site_domain', enabled=enabled) # Reasonably safe return str and bool
     sql_limit = sql_limit_offset_part(limit=limit, offset=offset) # Reasonably safe return str
 
-    # TODO: Add access_key to WHERE clause if provided, e.g.:
-    #   WHERE site_domain.fqdn = :fqdn AND (:access_key IS NULL OR site_domain.access_key = :access_key)
+    # Build access key / referrer SQL similar to router.lookup_fqdn behavior
+    if access_key and referrer:
+        sql_access_key_referrer = """
+            AND site_domain.domain_access_key = :domain_access_key
+            AND site_domain.required_referrer = :required_referrer
+            """
+    elif access_key:
+        sql_access_key_referrer = """
+            AND site_domain.domain_access_key = :domain_access_key
+            AND (site_domain.required_referrer IS NULL OR site_domain.required_referrer = '')
+            """
+    else:
+        sql_access_key_referrer = """
+            AND (site_domain.domain_access_key IS NULL OR site_domain.domain_access_key  = '')
+            AND (site_domain.required_referrer IS NULL OR site_domain.required_referrer  = '')
+            """
+
     sql = f"""
         SELECT `site_domain`.id AS 'site_domain_id', `site_domain`.id_random AS 'site_domain_id_random'
         FROM `v_site_domain` AS site_domain
         WHERE
             site_domain.fqdn = :fqdn
-            -- TODO: Add access_key check here for stricter validation
-            -- AND (:access_key IS NULL OR site_domain.access_key = :access_key)
+            {sql_access_key_referrer}
             {sql_enabled}
         ORDER BY `site_domain`.fqdn ASC, `site_domain`.access_key ASC, `site_domain`.required_referrer ASC, `site_domain`.created_on DESC, `site_domain`.updated_on DESC
         {sql_limit};
diff --git a/app/routers/site_domain.py b/app/routers/site_domain.py
index 8ccc603..4c9e98a 100644
--- a/app/routers/site_domain.py
+++ b/app/routers/site_domain.py
@@ -77,18 +77,20 @@ async def patch_site_domain_obj(
 @router.get('/site/domain/fqdn/{fqdn}', response_model=Resp_Body_Base)
 async def lookup_site_domain_obj(
         fqdn: str,
-        # x_account_id: str = Header(...),
-        # response: Response = Response,
-
-        commons: Common_Route_Params_Min = Depends(common_route_params_min),
+    # x_account_id: str = Header(...),
+    # response: Response = Response,
+    access_key: Optional[str] = Query(None, min_length=4, max_length=50),
+    referrer: Optional[str] = Query(None, min_length=8, max_length=150),
+    commons: Common_Route_Params_Min = Depends(common_route_params_min),
         ):
-    log.setLevel(logging.INFO) # DEBUG, INFO, WARNING, ERROR, EXCEPTION, CRITICAL
+    log.setLevel(logging.DEBUG) # DEBUG, INFO, WARNING, ERROR, EXCEPTION, CRITICAL
     log.debug(locals())
 
-
-     # Updated 2021-12-13
+    # Updated 2021-12-13
     if site_domain_rec_list_result := lookup_site_domain_fqdn(
             fqdn = fqdn,
+            access_key = access_key,
+            referrer = referrer,
             enabled = commons.enabled,
             limit = commons.limit,
             offset = commons.offset