[CentOS] "Site down for maintenance" - How is this accomplished?

[Feizhou]

Matt Arnilo S. Baluyos (Mailing Lists) wrote:
> Hello everyone,
> 
> Although we use CentOS primarily on our servers, this query is
> actually more of a general networking question than something specific
> to CentOS.
> 
> In the next week or so, we shall be migrating our in-house servers to
> a data center. While we're doing that, we'd like to show a "Site down
> for maintenance" message while the servers that hosts our websites (we
> have around 15 sites hosted btw), are down.
> 
> So, how is this accomplished? While I can probably hack something on
> our name servers, I'm sure there are people on this list that have
> been doing this and could give some recommendations as to the best
> practices for this type of task.

Keep or setup a box inhouse to show the message, when the servers are 
online in the data center, switch ips for the names over and then change 
  the setup on the box to either redirect or proxy the requests to the 
real servers to handle incoming http requests due to cached dns entries.