What is IP Address 169.254.X.X?

Question

Sometimes I have no internet access and when I check my local IP, i see 169.254.X.X (X = some random number).

Answer 1

According to RFC 5735: 

169.254.0.0/16 - This is the "link local" block.  As described in
   [RFC3927], it is allocated for communication between hosts on a
   single link.  Hosts obtain these addresses by auto-configuration,
   such as when a DHCP server cannot be found

 And RFC 3927 Section-1:

   This document describes a method by which a host may automatically
   configure an interface with an IPv4 address in the 169.254/16 prefix
   that is valid for Link-Local communication on that interface.  This
   is especially valuable in environments where no other configuration
   mechanism is available.  The IPv4 prefix 169.254/16 is registered
   with the IANA for this purpose.  Allocation of IPv6 Link-Local
   addresses is described in "IPv6 Stateless Address Autoconfiguration"
   [RFC2462].

Then, 169.254.0.0/16 is Link-Local Communication IP block that Operating System uses when there is no other IPv4 address assigned manually or by DHCP.

Answer 2

This will occur when your router cannot give you a local IP, so Your Operating System like Windows, iOS, Android or whatever, will give you an IP Address in range 169.254.0.0 - 169.254.255.255.

So, whenever you see this IP Address, just check your router and make sure DHCP Server is enabled.