Host header
A host header is that of an HTTP client as part of the HTTP header sent hostname . It can be used by an HTTP server to differentiate between virtual hosts and is therefore used in a broader sense for name resolution .
This name-based discrimination has virtual hosts (over IP-based virtual hosts) the advantage that different sites name
- can be operated under a common IP address (and under a common port )
- can still be managed separately in terms of content
and is therefore a way of dealing with a bottleneck in IP addresses.
To distinguish, the web server (to be configured accordingly) evaluates the host: header contained in the request .
configuration
In addition to adapting the configuration of the web server, make sure that the DNS server assigns the correct (in this case the same) IP address to each of the different host names.
Limits
- Some older http clients are not compatible with name-based virtual hosts. If such clients are also to be served, additional measures must be taken.
- With SSL / TLS -using servers to use is Server Name Indication necessary.
- Some bandwidth management techniques only work when different hosts have different IP addresses.