I thought that the loopback IP address of my machine is

I do not understand why am I able to ping IP addresses until

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    I think your question is off-topic here, but I would like to tell you that the entire range ( - is reserved for loopback purposes and they are always available. On most systems, localhost resolves to which is the most commonly used IPv4 loopback address. – Hung Tran Oct 2 '17 at 8:08
  • @HungTran Thank you for the information. So basically my own computer has many local IP addresses? – yoyo_fun Oct 2 '17 at 8:45
  • Yes, and the right term should be loopback IP addresses, NOT local. – Hung Tran Oct 2 '17 at 9:11
  • @HungTran Thank you, I understand. So the computer can have an IP address on the NIC and that is the local IP address, the IP assigned to the NIC. The loopback is a separate IP address but it is not assigned to the NIC it is just an internal IP address that the computer uses to communicate with itself. Am I correct? – yoyo_fun Oct 2 '17 at 9:14
  • Basically, we can understand like that. You can read more discussions here. – Hung Tran Oct 2 '17 at 9:36

The entire address block is the block of loopback addresses for a host. There are RFCs that explain this.

The goes back at least as far as RFC 990, ASSIGNED NUMBERS:

The class A network number 127 is assigned the "loopback" function, that is, a datagram sent by a higher level protocol to a network 127 address should loop back inside the host. No datagram "sent" to a network 127 address should ever appear on any network anywhere.

RFC 1122, Requirements for Internet Hosts -- Communication Layers:

(g) { 127, }

Internal host loopback address. Addresses of this form MUST NOT appear outside a host.

Also RFC 3330, Special-Use IPv4 Addresses: - This block is assigned for use as the Internet host loopback address. A datagram sent by a higher level protocol to an address anywhere within this block should loop back inside the host. This is ordinarily implemented using only for loopback, but no addresses within this block should ever appear on any network anywhere [RFC1700, page 5].

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