From what I read on: http://www.ietf.org/rfc/rfc3330.txt it seems it isn't required? and as long as your not using a "physical adapter" you should be able to use 127.0.0.1 for the loopback adapter. So why does Microsoft then NOT allow you to use 127.0.0.1 then with the MS loopback adapter? And why not have it there by default like the Linux community/distros already have?

What's the difference between having just the standard 127.0.0.1 localhost.localdomain in your host file, and adding the MS loopback adapter? Also, why can't you specify 127.0.01 with the MS Loopback adapter? Thanks

A/B) The problem is why given the standard is MS doing something different from the rest of the Linux community, or why the Linux community is doing something different from Microsoft. Is the standard to NOT allow the use of 127.0.0.1 with the adapter or is to have it there by default and TO use 127.0.0.1 vs. any other private IP addresses ? Why is there such a difference in implementation ? So is this an obigatory standard? C) Then why do Linux distrobutions include it there by default where as MS doesn't install a loopback adapter by default and have it use 127.0.0.1 like Linux distro's do? Are you saying the Linux community is mixing principals by having it there by default and having it use 127.0.0.1 where as MS is not ? example: lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:60071808 errors:0 dropped:0 overruns:0 frame:0 TX packets:60071808 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:37423606393 (34.8 GiB) TX bytes:37423606393 (34.8 GiB)

MS Loopback adapter is a dummy network card (no HW). It is a testing tool. 127.x.x.x is reserverd adddress for local host. http://www.tcpipguide.com/free/t_IPReservedPrivateandLoopbackAddresses.htm

Why doesn't MS install a local loopback adapter by default like other Linux OS's .. RHEL, Cent, SUSE etc ? and allow that to be 127.0.0.1 ?

A. What problem do you try to solve? B. There is standard for special addresses and operating system vendors should comply with it: http://www.ietf.org/rfc/rfc3330.txt http://www.ietf.org/rfc/rfc2373.txt C. How is using the MS Loopback Adapter any different than using 127.0.0.1? The loopback address, 127.0.0.1, is a special IP address that any networked computer (Windows, UNIX, or other) will recognize as addressing the local system. The MS Loopback Adapter is a driver that simulates having a physical network card. You can add any IP address to the MS Loopback Adapter and even use it to create routing loops. Since the MS Loopback Adapter is only a piece of software, your traffic doesn't go anywhere. The MS Loopback Adapter is generally used for testing purposes to trick software into thinking a network card is connected when there isn't a network connection available.

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go to the device manager>right click any select add legacy hardware>install the hardware manually>network adapters then wait for a second then select microsoft as a manufacture>select loopback adapter Darshana Jayathilake

a) Was a solution recommended by someone to resolve a proxy issue. b) interesting, so your saying that not all OS's comply with the standards and that in this case MS is, and the other OS's perhaps are not? c) Right, so with windows the 127.0.0.1 is just an ip address Windows knows is the loopback ip address, where as the MS Loopback adapter you can specify any private IP aka 192.x.x.x or 10.x.x..x but NOT 127.0.0.1 for some reason? Why is that? Why not have an adapter aka MS loopback Local Adapter like other Linux OS's that works with 127.0.0.1 by default? Why the separation there? With the option to add additional loopback adapters if you want/need other IP addresses aka 192.x.x.x. or 10.x.x.x ? thats what I'm not understanding as seeing some other Linux companies .. ie. RHEL, CentOS give that lo adapter to you and those CAN and do use 127.0.0.1. Why can't MS allow that adapter to use the 127.0.0.1 address? Just trying to understand.

A. I would apprecite if you could be more specific. Let us solve real problems, please. B. All operating system vendors including open ones try to comply with standards as much as possible. Usually they take place in creating process of standards. Some standards are obligatory some are not. C. You are mixing various principles. Loopback adapter is good for testing in virtual environment without physical NIC., while loopback address is a special IP address that is assined to local host. Whenever you ping to 127.0.0.1 in local host, only local host responds. Respond loops back locally and does not reach any other host.