When i redirected a single webpage to an address http://0.0.0, i also found that 0.0.0 is an alias of the network address, but since it is only 3 bytes, this seems to be strange. Why would chrome and system ping "accept" to use a 3-byte address which then redirect to my network address in-the-browser and get "It works!" because apache took over the my NA also. firefox 8.0 can't handle the same request chrome can and will show up a 400 Bad Request Error status.

I can: ping 0.0.0
I can redirect to using php function header() in chrome with the code 'Location: http://0.0.0'

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    I'm not sure how this is a security question. – Fund Monica's Lawsuit Jul 4 '19 at 20:50
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    This might interest you: This IP address can be written 121 different ways – Luc Jul 5 '19 at 9:57
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    Did you literally make a screenshot of an image saying Location: http://0.0.0 instead of writing it? What for? – MechMK1 Jul 5 '19 at 10:14
  • MechMK1 just another way of presenting code, but that doesn't matter – user211258 Jul 5 '19 at 10:26
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    "just another way of presenting code, but that doesn't matter" Actually, it does matter a great deal to people using tools such as screen readers, translation utilities and other usability enhancement tools. Stack Exchange sites see users from just about every part of the world and every walk of life; don't assume that just because using an image containing only text, instead of text, isn't a problem for you, that doing so won't be a problem for others. – a CVn Jul 6 '19 at 20:13

This is a relic of the original Internet addressing scheme, now retronymed 'classful' and obsolete almost 3 decades. See e.g. https://stackoverflow.com/questions/29285954/wsastringtoaddress-thinks-1-2-3-is-a-valid-ip-address or more officially http://pubs.opengroup.org/onlinepubs/009695399/functions/inet_addr.html . Note that itself, in whatever representation, cannot actually be a host address, but since it is the reserved special value INADDR_ANY some software replaces it with another address like which is routable, or close enough. OTOH you can't get a valid certificate for HTTPS/SSL/TLS for either or from any 'real' CA (more specifically, any CA subject to CABforum rules or trusted by any major browser).

Although this is primarily a programming-for-networking issue, there is a slight security impact in that nowadays 99.99% of systems on the Internet are operated by individuals (cf. Dilbert) with sub-fractional clues how the Internet actually works, so that phishers, scammers, etc. sometimes use these obsolete address formats (especially the single number) in URLs and email addresses to confuse, mislead, and deceive such people.

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Using IPv4, some zeros can be "optionnal" if easily guessable:

~$ ping 192.1
PING 192.1 ( 56(84) bytes of data.
--- 192.1 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1027ms

~$ ping 192.168.1
PING 192.168.1 ( 56(84) bytes of data.
--- 192.168.1 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

Nevertheless, i don't remember if the job is done by resolver or the software...

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