Fixed broken service tags link

Author: rezasherafat

articles/iot-hub/iot-hub-understand-ip-address.md

@@ -25,7 +25,7 @@ The IP address prefixes of IoT Hub public endpoints are published periodically u
 
 * When adding ALLOW rules in your devices' firewall configuration, it is best to provide specific [ports used by applicable protocols](./iot-hub-devguide-protocols.md#port-numbers).
 
-* The IP address prefixes of IoT hub are subject to change. These changes are published periodically via service tags before taking effect. It is therefore important that you develop processes to regularly retrieve and use the latest service tags. This process can be automated via the [service tags discovery API](../virtual-network/service-tags-overview.md#service-tags-in-on-premises).
+* The IP address prefixes of IoT hub are subject to change. These changes are published periodically via service tags before taking effect. It is therefore important that you develop processes to regularly retrieve and use the latest service tags. This process can be automated via the [service tags discovery API](../virtual-network/service-tags-overview.md#service-tags-on-premises).
 
 * Use the *AzureIoTHub.[region name]* tag to identify IP prefixes used by IoT hub endpoints in a specific region. To account for datacenter disaster recovery, or [regional failover](iot-hub-ha-dr.md) ensure connectivity to IP prefixes of your IoT Hub's geo-pair region is also enabled.
 
@@ -40,4 +40,4 @@ The IP address prefixes of IoT Hub public endpoints are published periodically u
 
 ## Support for IPv6 
 
-IPv6 is currently not supported on IoT Hub.
+IPv6 is currently not supported on IoT Hub.