Carrier-grade NAT address
100.64.0.1
100.64.0.1 is in 100.64.0.0/10, the shared address space ISPs use for carrier-grade NAT (RFC 6598). It isn't routed on the public internet, so there's nothing public to look up. 100.64.0.1 is the first usable address of the block, so ISPs often use it for the carrier-grade NAT gateway their customers' routers send traffic to. It shows up as an early hop in traceroutes.
At a glance
- Block
- 100.64.0.0/10
- Defined in
- RFC 6598
- On the public internet
- No
About this block
There aren't enough public IPv4 addresses for every customer, so many ISPs give each customer's router an address from 100.64.0.0/10 and translate many customers to one public address at the edge of their network. This is carrier-grade NAT (CGNAT).
The block was set aside in 2012 so ISPs wouldn't have to borrow private ranges that their customers' own networks already use. Like a private address, it only means something inside one ISP's network.
Where you'll see it
- As your router's WAN or internet address. Your ISP uses CGNAT: you share a public address with other customers, so incoming connections and port forwarding won't reach you unless the ISP gives you a public address or you use IPv6.
- As the first or second hop of a traceroute, where your traffic meets the ISP's NAT gateway.
- On Tailscale, which gives each device an address from this block (100.x.y.z).