Chapter 1: Introduction4APIPA and Link-Local AddressingThe EMX supports Automatic Private Internet Protocol Addressing(APIPA) as of release 3.2.0.With APIPA, your EMX automatically configures a link-local IP addressand a link-local host name when it cannot obtain a valid IP address fromany DHCP server in the TCP/IP network.Only IT devices connected to the same subnet can access the EMXusing the link-local address/host name. Those in a different subnetcannot access it.Exception: The EMX in the Port Forwarding mode does not supportAPIPA. See Setting the Cascading Mode (on page 136).Once the EMX can get a DHCP-assigned IP address, it stops usingAPIPA and the link-local address is replaced by the DHCP-assignedaddress.Scenarios where APIPA applies: DHCP is enabled on the EMX, but no IP address is assigned to theEMX.This may be caused by the absence or malfunction of DHCP serversin the network.Note: Configuration by connecting the EMX to a computer using anetwork cable is an application of this scenario. See Connecting theEMX to a Computer (on page 11). The EMX previously obtained an IP address from the DHCP server,but the lease of this IP address has expired, and the lease cannot berenewed, or no new IP address can be obtained.Link-local addressing: IPv4 address:Factory default is to enable IPv4 only. The link-local IPv4 address is169.254.x.x/16, which ranges between 169.254.1.0 and169.254.254.255. IPv6 address:A link-local IPv6 address is available only after IPv6 is enabled onthe EMX. See Selecting the Internet Protocol (on page 114). Host name - pdu.local:You can type https://pdu.local to access the EMX instead of typingthe link-local IP address.
