Most of you might wonder if two routers can share the same IP address.
So in this article, we discuss when two routers can share the same IP address and when they can’t.
We also explain what can happen in a router IP address conflict.
Here’s Whether Two Routers Can Have The Same IP Address:
Two routers on the same network can’t have the same IP address. On the other hand, two routers on different networks can have the same private IP address. Because public IP addresses should be unique, two routers can’t have the same public IP address.
Can Two Routers On The Same Network Have The Same IP Address?
Two routers on the same network can’t have the same IP address. If they have the same IP address, it will cause an IP conflict. In that case, one router will not get its traffic and can cause random behavior.
Most of the time, when a router detects an IP conflict, it will simply log the error and turn off the router interface.
Can Two Routers On Different Networks Have The Same Private IP Address?
Two routers on different networks can have the same private IP address. Because they are on different networks, using the same private IP does not cause an IP conflict.
This is actually the purpose of a private IP address. You can reuse the same private IP on different networks without causing IP conflicts.
Can Two Routers Have The Same Public IP Address?
Two routers can’t have the same public IP address. Public IP addresses should be unique, so only one device should have a given public IP address at a given time.
However, two routers from the same ISP might show the same public IP address when checked with sites like whatsmyip.org. In that case, the two routers are sharing a single public IP address using ISP carrier-grade NAT.
With carrier-grade NAT, each router gets a private WAN IP address from the ISP, and the ISP combines the traffic from multiple customers to a single public IP address.
Can Two Routers Have The Same WAN IP Address?
Two routers can’t have the same WAN IP address when both WAN IPs are public. Public IPs should be unique.
On the other hand, if your router’s WAN IP is private to the ISP, a different ISP’s router can have the same private WAN IP. This can happen when both ISPs use carrier-grade NAT with the same private IP address spaces.
However, the private WAN IP should be unique within a given ISP.
What Happens When Two Routers On The Same LAN Have The Same IP Address?
When two routers on the same LAN have the same IP address, it will cause an IP conflict. So one router will report an error and then turn off its network interface.
You have to change the IP addresses of the conflicting routers to resolve the issue.
Conclusion
Two routers on the same network can’t have the same IP address. If they have the same IP, it will cause an IP conflict, and one router will turn off its network interface.
On the other hand, two routers on different networks can have the same private IP address. Because the routers are on different networks, it won’t cause IP conflicts.
Finally, two routers can’t have the same public IP address. Public IP addresses, by definition, should be unique.