127.0.0.1 (localhost)
127.0.0.1 is the IPv4 loopback address — it always refers to the local machine itself. Traffic to it never leaves the device.
What it is used for
It is used to test the local TCP/IP stack and to reach services running on the same computer.
Where you will see it
Understanding reserved addresses like this is core CCNA knowledge — they appear constantly in routing tables, DHCP and troubleshooting.
Frequently asked questions
What is 127.0.0.1?
127.0.0.1 is the IPv4 loopback address — it always refers to the local machine itself. Traffic to it never leaves the device.
Is 127.0.0.1 routable on the internet?
No — it is a reserved special-purpose address and is not routed on the public internet.
Where is it used?
It is used to test the local TCP/IP stack and to reach services running on the same computer.
Related
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