Understanding Packet Level for IP 127.0.0.1 and Localhost

  • Thread starter Chromium
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In summary, when typing in "localhost" or "127.0.0.1", your computer's internal name-resolver program is automatically called and redirects the request back to your local machine. This is because any loopback address outside of your computer will be dropped, making it faster to handle requests locally.
  • #1
Chromium
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hey everyone,

so I know that 127.0.0.1 or localhost just loops back to your local machine. However, I don't understand what occurs on the packet level when you actually type in 'localhost' or '127.0.0.1' One of my co-workers speculated that each computer has some sort of internal name-resolver program that, when a user types in those special strings, is automatically called & just re-directs back to the local computer. Does this sound valid?

Does anyone know what exactly happens on the packet level?

thanks,

--Jonathan
 
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  • #2
Chromium said:
One of my co-workers speculated that each computer has some sort of internal name-resolver program that, when a user types in those special strings, is automatically called & just re-directs back to the local computer. Does this sound valid?

Yep, that's pretty much it. Anything outside your computer that somehow gets a loopback address will just drop it anyway, so your computer has to handle it. This is what you want, of course, since it's much faster than a real network connection.
 

Question 1: What is the IP address 127.0.0.1 used for?

The IP address 127.0.0.1 is a special address used to refer to the loopback interface of a computer. It is commonly known as the "localhost" address, and it allows a computer to send and receive data from itself.

Question 2: Why is 127.0.0.1 used as the default IP address for localhost?

The address 127.0.0.1 was designated as the loopback address in the early stages of the development of the Internet Protocol (IP) as it falls within the reserved range of IP addresses that are not assigned to any specific network.

Question 3: Can 127.0.0.1 be used as a public IP address?

No, 127.0.0.1 is a private IP address and cannot be used as a public IP address. It is reserved for use within a local network and cannot be accessed from the internet.

Question 4: What is the significance of the IP address 127.0.0.1 in network troubleshooting?

The IP address 127.0.0.1 can be used for network troubleshooting to test whether the network interface card (NIC) is functioning properly. By sending data to this address, the computer can determine if the NIC is able to receive and process data.

Question 5: Can the IP address 127.0.0.1 be changed or modified?

No, the IP address 127.0.0.1 is a reserved address and cannot be changed or modified. It is hard-coded into the network stack of a computer and is used for specific purposes, such as referring to the local host.

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