Setting the `STD_CDEFINES` environment variable before running `configure` can be used to enable certain compile-time options that are not explicitly defined in `configure`. Some of these settings are: |Setting |Description | |-----------------------------------|----------------------------------------| |`-DISC_MEM_DEFAULTFILL=1`|Overwrite memory with tag values when allocating or freeing it; this impairs performance but makes debugging of memory problems easier.| |`-DISC_MEM_TRACKLINES=0`|Don't track memory allocations by file and line number; this improves performance but makes debugging more difficult.| |`-DISC_FACILITY=LOG_LOCAL0`|Change the default syslog facility for `named`| |`-DNS_CLIENT_DROPPORT=0`|Disable dropping queries from particular well-known ports:| |`-DCHECK_SIBLING=0`|Don't check sibling glue in `named-checkzone`| |`-DCHECK_LOCAL=0`|Don't check out-of-zone addresses in `named-checkzone`| |`-DNS_RUN_PID_DIR=0`|Create default PID files in `${localstatedir}/run` rather than `${localstatedir}/run/named/`| |`-DISC_BUFFER_USEINLINE=0`|Disable the use of inline functions to implement the `isc_buffer` API: this reduces performance but may be useful when debugging | |`-DISC_HEAP_CHECK`|Test heap consistency after every heap operation; used when debugging|