diff --git a/scripts/nbhelper/service.py b/scripts/nbhelper/service.py
index 1ad992c..fe78a9f 100644
--- a/scripts/nbhelper/service.py
+++ b/scripts/nbhelper/service.py
@@ -4,12 +4,9 @@
 # SPDX-License-Identifier: Apache-2.0
 
 # service.py
-#
 
-import re
 import netaddr
 
-from .utils import logger, AttrDict
 from .container import ServiceInfoContainer
 
 
@@ -66,7 +63,7 @@
             for host in domain["hosts"]:
                 if ip_address == host["ip_addr"]:
                     return f"{host['name']}.{domainName}."
-
+        return ""
 
     dnsForwardZoneConfigs = dict()
 
@@ -91,7 +88,9 @@
         if ntpServer:
             forwardZoneConfig["cname"]["ntp"] = getDomainNameByIP(ntpServer["address"])
         if dhcpServer:
-            forwardZoneConfig["cname"]["tftp"] = getDomainNameByIP(dhcpServer["address"])
+            forwardZoneConfig["cname"]["tftp"] = getDomainNameByIP(
+                dhcpServer["address"]
+            )
         if dnsServer:
             forwardZoneConfig["cname"]["ns"] = getDomainNameByIP(dnsServer["address"])
             forwardZoneConfig["ns"].append(getDomainNameByIP(dnsServer["address"]))
@@ -126,7 +125,7 @@
         if o1 == 10:
             o2 = o3 = o4 = 0
             cidr_plen = 8
-        elif (o1 == 172 and o2 >= 16 and o2 <= 31) or (o1 == 192 and o2 == 168):
+        elif (o1 == 172 and 16 <= o2 <= 31) or (o1 == 192 and o2 == 168):
             o3 = o4 = 0
             cidr_plen = 16