The variable gnus-nntp-server specifies the default NNTP
server. To define the server `flab', put the following code in
`.emacs', `site-init.el' or `default.el':
(setq gnus-nntp-server "flab")
The variable gnus-nntp-server is initialized from the
NNTPSERVER environment variable. To define the server using the
NNTPSERVER environment variable, put the following code in
`.login':
setenv NNTPSERVER "flab"
If an NNTP server is preceded by a colon such as `:Mail', the user's private directory `~/Mail' is used as the news spool. This makes it possible to read mail stored in MH folders or articles saved by GNUS. See section Reading a Private Directory, for more information.
GNUS will ask you for the NNTP server at start up time unless it is defined. Even if the default server is defined, it is possible to choose another server by invoking GNUS with a prefix argument like C-u M-x gnus (see section Getting Started GNUS).