I'm seeing behavior from my mac mini that is confusing me, I'm hoping someone else has seen this before;

When connecting to my mac mini from my macbook pro, connecting to the computer name is instant but connecting to the IP takes several seconds (10-15). This seems counter-intuitive to me, because connecting to a name involves the extra step of looking up the name I would think that connecting to the IP would be instant.

Does anyone know why this is, or how to eliminate the delay?

  • Please give more details on the problem. E.g. what type of connection are you making (e.g. file sharing in the Finder, SSH, screen sharing, etc), what computer name are you using (e.g. a .local name, full DNS name, etc), and what's your network setup like (e.g. both on wireless behind home router)? – Gordon Davisson Jul 10 '11 at 1:47
  • Vnc connection, using computer name "zim" which is set to an ip when the computer joins the network via dynamic dns. Network is fairly simple, dhcp but with a dns server for names on the local network. Both computers are on the same switch. Connecting via Debian does not produce this delay. – Jeff Welling Jul 10 '11 at 2:32

This is just a guess, but when you use the IP address it may try to do a reverse DNS lookup to get the associated name, and take a while to time out.

  • You can test this good idea by timing various ping x and ping -n y keep changing the address to avoid cache speedups. big web sites usually have wwwX for at least 10 addresses aliased to the main www – bmike Jul 16 '11 at 20:23

When you connect by name you're probably connecting to the IPv6 link local address instead of the v4 address.

  • That sounds like it could be why the name connects so fast, but I don't think that explains why trying to connect to an ipv4 address would take so long.. Do you think it's treating the ipv4 address as ipv6? – Jeff Welling Jul 10 '11 at 2:38
  • 1
    No. The remote side is probably doing a reverse DNS lookup against your v4 address which times out. – bahamat Jul 10 '11 at 23:31

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