The Short Answer: DHCP
For most home broadband and mobile users, IP addresses are not permanent. Your ISP uses DHCP (Dynamic Host Configuration Protocol) to assign an IP address to your router from a shared pool. That assignment comes with a lease time — a countdown after which the address must be renewed or returned to the pool. This is why your IP can — and does — change over time.
You can check your current public IP at any time using the What's My IP tool. For background on static versus dynamic assignment, see our guide on static IP vs. dynamic IP.
How DHCP Leases Work
When your router connects to your ISP, it broadcasts a DHCP request. Your ISP's DHCP server responds by assigning an available IP address along with a lease time — typically between 24 hours and 7 days. Before the lease expires, your router automatically sends a renewal request. If the same IP is still available, the ISP renews it and your address stays the same. If it has been reassigned or the renewal fails, a new IP is given.
This means that a router that has been powered on continuously for weeks may keep the same IP for the entire time, even though the address is technically "dynamic".
Common Causes of IP Address Changes
Causes and Likelihood
| Cause | Likelihood of IP Change | Notes |
|---|---|---|
| Router reboot / power cycle | Moderate | Depends on ISP sticky DHCP; often same IP is re-assigned |
| Extended outage (hours) | High | Lease may expire; ISP assigns new address |
| DHCP lease expiry | Low (while connected) | Routers renew automatically; same IP usually kept |
| CGNAT rotation (mobile) | Very High | Common on Du mobile and some e& mobile plans |
| Cell tower handoff | Moderate to High | Moving between towers can trigger IP rotation on mobile |
| ISP network maintenance | Moderate | Planned or emergency maintenance can force lease renegotiation |
| Switching ISP or plan | Certain | Completely new IP pool from the new ISP |
| Static IP configured | Never | Fixed address — does not change under any of the above |
Router Reboots
Rebooting your router is the most common trigger users notice. When the router powers back on, it sends a new DHCP request to your ISP. Many ISPs use sticky DHCP, where they track the router's hardware identifier (MAC address) and deliberately re-assign the same IP. However, if the lease expired during the downtime, or if the ISP has restructured its address pool, you will receive a new address.
CGNAT on Mobile Networks
Mobile networks — including Du mobile and some e& mobile plans in the UAE — typically use CGNAT (Carrier-Grade NAT). Under CGNAT, many customers share a single public IP address, with the carrier's infrastructure handling the translation internally. The apparent public IP can change even mid-session as you move between cell towers or as the carrier rebalances network load.
This is why your IP often looks different when using mobile data versus your home Wi-Fi. To understand CGNAT in depth, see our guide on static IP vs. dynamic IP.
ISP Maintenance and Network Restructuring
ISPs occasionally perform planned maintenance, replace equipment, or restructure their IP address allocations. During these events, customers' DHCP leases may not be renewed with the same address, resulting in a new IP even without any action on your part. This is normal and not a sign of a problem with your connection.
When Your IP Will NOT Change
- Static IP — A fixed address paid for as a business add-on from e& or Du. Never changes.
- Very long DHCP lease on a stable connection — A router that has been online for weeks with the same ISP may hold the same dynamic IP for the entire period.
- ISP sticky DHCP — Some ISPs almost always re-assign the same IP to the same router MAC address after a reboot, making the address effectively stable in practice.
How to Check If Your IP Changed
The simplest method:
- Visit What's My IP and note your current address.
- Perform the action you want to test (reboot router, wait, etc.).
- Visit the tool again and compare the address.
How to Get a Stable IP Address
- Request a static IP from your ISP — Both e& and Du offer static IPs as paid business add-ons. This is the most reliable solution. See our guide on static vs. dynamic IP for details.
- Use Dynamic DNS (DDNS) — Services like No-IP or DuckDNS map a fixed hostname to your current dynamic IP and update automatically on change. This does not prevent the IP from changing but makes it less disruptive for hosting purposes.
- Use a VPN with a dedicated IP — Some VPN providers offer a fixed IP address as an add-on. Your traffic exits through that fixed address regardless of your underlying ISP assignment. See our guide on what a VPN is.
- Keep your router powered on — Simply avoiding router reboots and maintaining a stable connection reduces the frequency of DHCP reassignments.
If you want to actively change your IP address on demand, our guide on how to renew your IP address covers the step-by-step methods for each platform.