Why Does My External IP Keep Changing?
Your external IP address can change for several reasons depending on how your internet connection is set up. Here are some common factors:
Dynamic IP Addressing
The vast majority of Internet Service Providers (ISPs) use dynamic IP addressing, which means your external IP can change periodically. This is managed by the Dynamic Host Configuration Protocol (DHCP). Through DHCP, ISPs assign IP addresses from a pool, allowing them to efficiently manage a finite resource of IPv4 addresses. Since IPv4 addresses are 32-bit numbers, they provide around 4 billion possible addresses, but in practice, this number is much less due to how they are distributed. Your ISP has a block of addresses, which is usually fewer than the total number of customer devices they need to support.
Furthermore, not all devices need to be online simultaneously, and many can be grouped together and hide behind a single public address using Network Address_translation (NAT). However, ISPs still need the capability to change IP address assignments, especially for mobile devices.
Router Reboot and Modem Reset
Restarting your router or modem can lead to a new IP address being assigned by your ISP. This is particularly common if you frequently reboot your home network equipment. Every time your router or modem is restarted, it may request a new IP address from your ISP, leading to a change in your external IP address.
ISP Policies
Some ISPs have policies that periodically change IP addresses to manage their networks more effectively. This is often done to ensure that all devices are being managed efficiently and to reset network configurations, which can help prevent security issues or network instability.
Network Changes
Connecting to a different network, such as moving from home Wi-Fi to mobile data, will result in a change in your external IP address. This is because your device is now assigned a new IP address from a different ISP or network provider.
Lease Time
The lease time assigned to your IP address by your ISP may expire, prompting the assignment of a new address. A typical DHCP lease is usually 24 or 48 hours. When this lease expires, your device will be assigned a new IP address, which may result in a change in your external IP. ISPs often set this lease time to allow for easy reassignment of IP addresses and to keep track of active connections.
Connection Type
The frequency of IP address changes depends on the type of connection you have. For instance, if you are using a mobile data connection, your IP address may change more frequently compared to a fixed broadband connection. This is because mobile data networks often require more dynamic IP addressing to accommodate numerous devices and network changes.
Static IP Address Request
If you need a static IP address that doesn't change, you can usually request this from your ISP. However, it often comes with an additional fee. Static IP addresses are beneficial for various scenarios, such as hosting websites, running servers, or ensuring stable connections for specific network configurations.
While IPv4 addresses are a finite resource, ISPs use dynamic IP addressing strategies to manage their limited pool of addresses efficiently. Understanding these factors can help you troubleshoot and resolve issues related to your external IP address.