Noun. 1. achromatic color-a color lacking hue; white or grey or black. achromatic colour. color, coloring, colouring, colour-a visual attribute of things that results from the light they emit or transmit or reflect; a white color is made up of many different wavelengths of light.
A good candidate for a mail host is a system that connects your systems to the outside world or to a parent domain. 1  Become superuser on the mail host system. 2  Verify the host name configuration. 3  Update. Create an entry for the new mail host in the appropriate hosts file.  Change the correct configuration 1  file. Restart and test your mail configuration.
In common usage today, hostname refers specifically to the FQDN that comprises the name of the host, a period, and the domain name. The domain name is composed of labels that begin with the top-level domain and are arranged right to left for the second and, possibly, third level labels. complete domain name (that is, an FQDN) includes the name of the host concatenated with its domain name. This naming convention allows for a hierarchy of domain names with the host name being the most specific (and left-most) part.