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I have a Windows 7 computer and a MacOS X 10.6 computer that are connected to the same LAN using a 10$ hub. On MacOS I set the computer name to "mymac.local" in "preferences->sharing". The Windows computer has a static IP address of 192.168.0.10 and the Mac has the address 192.168.0.20. Both have a netmask of 255.255.255.0 and no gateway.

If I issue the command ping mymac.local from my Windows computer it will successfully ping 192.168.0.20. How did Windows determine that IP 192.168.0.20 is associated with "mymac.local" since there's no DNS on my network? Is it some broadcast? What protocol is used?

5

It resolves the .local names using multicast DNS (RFC 6762) as part of zero-configuration networking.

  • Yes, installing bonjour enables ping by name. It is not working without bonjour. – grigoryvp Mar 4 '11 at 19:07
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It uses the (ancient) NETBIOS protocol and the Windows implementation of its name service, WINS. If a name cannot be resolved by the DNS servers the WINS server is tried or if it isn't defined a NEBIOS call is made.

Note that some routers include a DNS server and add to it the name each DHCP clients provides. If your router supports this capability, then the DNS protocol is actually being used to resolve the name resolution query.

  • 1
    When you see .local as part of the name it's much more likely to be zeroconf than NETBIOS. – sciurus Mar 6 '11 at 0:42

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