network status

https://tools.ietf.org/html/rfc7231#section-6

The first digit of the status-code defines the class of response.
   The last two digits do not have any categorization role.  There are
   five values for the first digit:

   o  1xx (Informational): The request was received, continuing process

   o  2xx (Successful): The request was successfully received,
      understood, and accepted

   o  3xx (Redirection): Further action needs to be taken in order to
      complete the request

   o  4xx (Client Error): The request contains bad syntax or cannot be
      fulfilled

   o  5xx (Server Error): The server failed to fulfill an apparently
      valid request