diff --git a/RELNOTES b/RELNOTES
index dd06e76e..3fe70bac 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -54,6 +54,9 @@ work on other platforms. Please report any problems and suggested fixes to
   via two ./configure parameters, --enable-paranoia and
   --enable-early-chroot.
 
+- ./configure was extended to cover many optional build features, such
+  as failover, server tracing, debugging, and the execute() command.
+
 			Changes since 4.0.0 (new features)
 
 - Added DHCPv6 rapid commit support.
diff --git a/common/execute.c b/common/execute.c
index ac63b084..0e8ef18c 100644
--- a/common/execute.c
+++ b/common/execute.c
@@ -729,8 +729,10 @@ void write_statements (file, statements, indent)
 	struct executable_statement *statements;
 	int indent;
 {
-	struct executable_statement *r, *x;
+#if defined ENABLE_EXECUTE
 	struct expression *expr;
+#endif
+	struct executable_statement *r, *x;
 	const char *s, *t, *dot;
 	int col;
 
diff --git a/common/parse.c b/common/parse.c
index 041a0de8..eea0925e 100644
--- a/common/parse.c
+++ b/common/parse.c
@@ -2017,13 +2017,15 @@ int parse_executable_statement (result, cfile, lose, case_context)
 	int *lose;
 	enum expression_context case_context;
 {
+#if defined(ENABLE_EXECUTE)
+	unsigned len;
+	struct expression **ep;
+#endif
 	enum dhcp_token token;
 	const char *val;
-	unsigned len;
 	struct class *cta;
 	struct option *option=NULL;
 	struct option_cache *cache;
-	struct expression **ep;
 	int known;
 	int flag;
 	int i;
diff --git a/configure.ac b/configure.ac
index f09ad129..24a76785 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,10 +30,72 @@ AC_DEFINE_UNQUOTED([DHCP_BYTE_ORDER], [$byte_order],
 		   [Define to BIG_ENDIAN for MSB (Motorola or SPARC CPUs)
 		    or LITTLE_ENDIAN for LSB (Intel CPUs).])
 
-# DHCPv6 is off by default
+# Optional compile-time DEBUGging.
+AC_ARG_ENABLE(debug,
+	AC_HELP_STRING([--enable-debug],
+		[create a debug-only version of the software (default is no).]))
+# This is very much off by default.
+if test "$enable_debug" = "yes" ; then
+	AC_DEFINE([DEBUG], [1],
+		[Define to compile debug-only DHCP software.])
+	# Just override CFLAGS to totally to remove optimization.
+	CFLAGS="-g"
+fi
+# XXX: there are actually quite a lot more DEBUG_ features we could enable,
+# but I don't want to pollute the --help space.
+#
+#/* #define DEBUG_TOKENS */
+#/* #define DEBUG_PACKET */
+#/* #define DEBUG_EXPRESSIONS */
+#/* #define DEBUG_FIND_LEASE */
+#/* #define DEBUG_EXPRESSION_PARSE */
+#/* #define DEBUG_CLASS_MATCHING */
+#/* #define DEBUG_MEMORY_LEAKAGE */
+#/* #define DEBUG_MALLOC_POOL */
+#/* #define DEBUG_LEASE_STATE_TRANSITIONS */
+#/* #define DEBUG_RC_HISTORY */
+#/* #define DEBUG_RC_HISTORY_EXHAUSTIVELY */
+#/* #define RC_HISTORY_MAX 10240 */
+#/* #define POINTER_DEBUG */
+#/* #define DEBUG_FAILOVER_MESSAGES */
+#/* #define DEBUG_FAILOVER_TIMING */
+#/* #define DEBUG_DUMP_ALL_LEASES */
+
+# Failover optional compile-time feature.
+AC_ARG_ENABLE(failover,
+	AC_HELP_STRING([--enable-failover],
+		[enable support for failover (default is yes)]))
+# Failover is on by default, so define if it is not explicitly disabled.
+if test "$enable_failover" != "no"; then
+	AC_DEFINE([FAILOVER_PROTOCOL], [1],
+		  [Define to include Failover Protocol support.])
+fi
+
+# execute() support.
+AC_ARG_ENABLE(execute,
+	AC_HELP_STRING([--enable-execute],
+		[enable support for execute() in config (default is yes)]))
+# execute() is on by default, so define if it is not explicitly disabled.
+if test "$enable_execute" != "no" ; then
+	AC_DEFINE([ENABLE_EXECUTE], [1],
+		  [Define to include execute() config language support.])
+fi
+
+# Server tracing support.
+AC_ARG_ENABLE(tracing,
+	AC_HELP_STRING([--enable-tracing],
+		[enable support for server activity tracing (default is yes)]))
+# tracing is on by default, so define if it is not explicitly disabled.
+if test "$enable_tracing" != "no" ; then
+	AC_DEFINE([TRACING], [1],
+		  [Define to include server activity tracing support.])
+fi
+
+# DHCPv6 optional compile-time feature.
 AC_ARG_ENABLE(dhcpv6,
 	AC_HELP_STRING([--enable-dhcpv6],
 		       [enable support for DHCPv6 (default is yes)]))
+# DHCPv6 is on by default, so define if it is not explicitly disabled.
 if test "$enable_dhcpv6" != "no"; then
 	AC_DEFINE([DHCPv6], [1], 
 		  [Define to 1 to include DHCPv6 support.])
diff --git a/includes/site.h b/includes/site.h
index 98d33254..dc81ae7b 100644
--- a/includes/site.h
+++ b/includes/site.h
@@ -94,7 +94,7 @@
 /* Define this if you want DHCP failover protocol support in the DHCP
    server. */
 
-#define FAILOVER_PROTOCOL
+/* #define FAILOVER_PROTOCOL */
 
 /* Define this if you want DNS update functionality to be available. */
 
@@ -171,7 +171,7 @@
 /* Define this if you want to be able to execute external commands
    during conditional evaluation. */
 
-#define ENABLE_EXECUTE
+/* #define ENABLE_EXECUTE */
 
 /* Define this if you aren't debugging and you want to save memory
    (potentially a _lot_ of memory) by allocating leases in chunks rather
@@ -182,4 +182,4 @@
 /* Define this if you want to be able to save and playback server operational
    traces. */
 
-#define TRACING
+/* #define TRACING */
diff --git a/minires/res_init.c b/minires/res_init.c
index b96b326b..b38fdbf0 100644
--- a/minires/res_init.c
+++ b/minires/res_init.c
@@ -76,7 +76,7 @@
 
 #if defined(LIBC_SCCS) && !defined(lint)
 static const char sccsid[] = "@(#)res_init.c	8.1 (Berkeley) 6/7/93";
-static const char rcsid[] = "$Id: res_init.c,v 1.10 2007/10/01 14:47:35 explorer Exp $";
+static const char rcsid[] = "$Id: res_init.c,v 1.11 2008/02/28 21:21:56 dhankins Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/types.h>
@@ -99,7 +99,6 @@ static const char rcsid[] = "$Id: res_init.c,v 1.10 2007/10/01 14:47:35 explorer
 /* Options.  Should all be left alone. */
 #define RESOLVSORT
 #define RFC1535
-#define DEBUG
 
 static void res_setoptions (res_state, const char *, const char *);
 
@@ -389,14 +388,12 @@ minires_vinit(res_state statp, int preinit) {
 			dots--;
 		}
 		*pp = NULL;
-#ifdef DEBUG
 		if (statp->options & RES_DEBUG) {
 			printf(";; res_init()... default dnsrch list:\n");
 			for (pp = statp->dnsrch; *pp; pp++)
 				printf(";;\t%s\n", *pp);
 			printf(";;\t..END..\n");
 		}
-#endif
 #endif /* !RFC1535 */
 	}
 
@@ -411,11 +408,9 @@ res_setoptions(res_state statp, const char *options, const char *source) {
 	const char *cp = options;
 	int i;
 
-#ifdef DEBUG
 	if (statp->options & RES_DEBUG)
 		printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 		       options, source);
-#endif
 	while (*cp) {
 		/* skip leading and inner runs of spaces */
 		while (*cp == ' ' || *cp == '\t')
@@ -427,10 +422,8 @@ res_setoptions(res_state statp, const char *options, const char *source) {
 				statp->ndots = i;
 			else
 				statp->ndots = RES_MAXNDOTS;
-#ifdef DEBUG
 			if (statp->options & RES_DEBUG)
 				printf(";;\tndots=%d\n", statp->ndots);
-#endif
 		} else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 			i = atoi(cp + sizeof("timeout:") - 1);
 			if (i <= RES_MAXRETRANS)
@@ -444,14 +437,12 @@ res_setoptions(res_state statp, const char *options, const char *source) {
 			else
 				statp->retry = RES_MAXRETRY;
 		} else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
-#ifdef DEBUG
 			if (!(statp->options & RES_DEBUG)) {
 				printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 				       options, source);
 				statp->options |= RES_DEBUG;
 			}
 			printf(";;\tdebug\n");
-#endif
 		} else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
 			statp->options |= RES_USE_INET6;
 		} else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
diff --git a/minires/res_mkupdate.c b/minires/res_mkupdate.c
index f8d84004..368bcb05 100644
--- a/minires/res_mkupdate.c
+++ b/minires/res_mkupdate.c
@@ -27,7 +27,7 @@
  */
 
 #if !defined(lint) && !defined(SABER)
-static const char rcsid[] = "$Id: res_mkupdate.c,v 1.11 2007/07/13 06:43:42 shane Exp $";
+static const char rcsid[] = "$Id: res_mkupdate.c,v 1.12 2008/02/28 21:21:56 dhankins Exp $";
 #endif /* not lint */
 
 #include <sys/types.h>
@@ -50,7 +50,6 @@ static const char rcsid[] = "$Id: res_mkupdate.c,v 1.11 2007/07/13 06:43:42 shan
 #include "arpa/nameser.h"
 
 /* Options.  Leave them on. */
-#define DEBUG
 #define MAXPORT 1024
 
 static int getnum_str(const u_char **, const u_char *);
diff --git a/minires/res_query.c b/minires/res_query.c
index ff119e4c..606c984c 100644
--- a/minires/res_query.c
+++ b/minires/res_query.c
@@ -76,7 +76,7 @@
 
 #if defined(LIBC_SCCS) && !defined(lint)
 static const char sccsid[] = "@(#)res_query.c	8.1 (Berkeley) 6/4/93";
-static const char rcsid[] = "$Id: res_query.c,v 1.8 2007/09/05 17:32:10 dhankins Exp $";
+static const char rcsid[] = "$Id: res_query.c,v 1.9 2008/02/28 21:21:56 dhankins Exp $";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/types.h>
@@ -95,8 +95,6 @@ static const char rcsid[] = "$Id: res_query.c,v 1.8 2007/09/05 17:32:10 dhankins
 #include "arpa/nameser.h"
 
 /* Options.  Leave them on. */
-#define DEBUG
-
 #if PACKETSZ > 1024
 #define MAXPACKET	PACKETSZ
 #else
@@ -128,37 +126,29 @@ res_nquery(res_state statp,
 
 	hp->rcode = NOERROR;	/* default */
 
-#ifdef DEBUG
 	if (statp->options & RES_DEBUG)
 		printf(";; res_query(%s, %d, %d)\n", name, class, type);
-#endif
 
 	rcode = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 			     buf, sizeof(buf), &n);
 	if (rcode != ISC_R_SUCCESS) {
-#ifdef DEBUG
 		if (statp->options & RES_DEBUG)
 			printf(";; res_query: mkquery failed\n");
-#endif
 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
 		return rcode;
 	}
 	rcode = res_nsend(statp, buf, n, answer, anslen, &n);
 	if (rcode != ISC_R_SUCCESS) {
-#ifdef DEBUG
 		if (statp->options & RES_DEBUG)
 			printf(";; res_query: send error\n");
-#endif
 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
 		return rcode;
 	}
 
 	if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
-#ifdef DEBUG
 		if (statp->options & RES_DEBUG)
 			printf(";; rcode = %d, ancount=%d\n", hp->rcode,
 			    ntohs(hp->ancount));
-#endif
 		switch (hp->rcode) {
 		case NXDOMAIN:
 			RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
@@ -347,11 +337,9 @@ res_nquerydomain(res_state statp,
 	const char *longname = nbuf;
 	int n, d;
 
-#ifdef DEBUG
 	if (statp->options & RES_DEBUG)
 		printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 		       name, domain?domain:"<Nil>", class, type);
-#endif
 	if (domain == NULL) {
 		/*
 		 * Check for trailing '.';
diff --git a/omapip/buffer.c b/omapip/buffer.c
index 4e851280..4204574c 100644
--- a/omapip/buffer.c
+++ b/omapip/buffer.c
@@ -442,7 +442,6 @@ isc_result_t omapi_connection_writer (omapi_object_t *h)
 	unsigned first_byte;
 	omapi_buffer_t *buffer;
 	omapi_connection_object_t *c;
-	isc_result_t status;
 
 	if (!h || h -> type != omapi_type_connection)
 		return ISC_R_INVALIDARG;
@@ -504,6 +503,7 @@ isc_result_t omapi_connection_writer (omapi_object_t *h)
 
 #if defined (TRACING)
 			if (trace_record ()) {
+				isc_result_t status;
 				trace_iov_t iov [2];
 				int32_t connect_index;
 				
diff --git a/omapip/connection.c b/omapip/connection.c
index 618eaa75..93509696 100644
--- a/omapip/connection.c
+++ b/omapip/connection.c
@@ -437,7 +437,6 @@ isc_result_t omapi_disconnect (omapi_object_t *h,
 			       int force)
 {
 	omapi_connection_object_t *c;
-	isc_result_t status;
 
 #ifdef DEBUG_PROTOCOL
 	log_debug ("omapi_disconnect(%s)", force ? "force" : "");
@@ -449,6 +448,7 @@ isc_result_t omapi_disconnect (omapi_object_t *h,
 
 #if defined (TRACING)
 	if (trace_record ()) {
+		isc_result_t status;
 		int32_t index;
 
 		index = htonl (c -> index);
diff --git a/omapip/mrtrace.c b/omapip/mrtrace.c
index 838e304c..c3fe8606 100644
--- a/omapip/mrtrace.c
+++ b/omapip/mrtrace.c
@@ -38,6 +38,7 @@
 
 #include <errno.h>
 
+#if defined(TRACING)
 static void trace_mr_output_input (trace_type_t *, unsigned, char *);
 static void trace_mr_output_stop (trace_type_t *);
 static void trace_mr_input_input (trace_type_t *, unsigned, char *);
@@ -46,6 +47,7 @@ static void trace_mr_statp_input (trace_type_t *, unsigned, char *);
 static void trace_mr_statp_stop (trace_type_t *);
 static void trace_mr_randomid_input (trace_type_t *, unsigned, char *);
 static void trace_mr_randomid_stop (trace_type_t *);
+#endif /* TRACING */
 trace_type_t *trace_mr_output;
 trace_type_t *trace_mr_input;
 trace_type_t *trace_mr_statp;
@@ -404,9 +406,9 @@ int trace_mr_select (int s, fd_set *r, fd_set *w, fd_set *x, struct timeval *t)
 
 unsigned int trace_mr_res_randomid (unsigned int oldid)
 {
-	u_int32_t id;
 	int rid = oldid;
 #if defined (TRACING)
+	u_int32_t id;
 	unsigned buflen = 0;
 	char *buf = (char *)0;
 	isc_result_t status;
diff --git a/server/dhcp.c b/server/dhcp.c
index 93a594ac..7376932e 100644
--- a/server/dhcp.c
+++ b/server/dhcp.c
@@ -796,7 +796,9 @@ void dhcprelease (packet, ms_nulltp)
 		release_lease (lease, packet);
 	} 
 	log_info ("%s", msgbuf);
+#if defined(FAILOVER_PROTOCOL)
       out:
+#endif
 	if (lease)
 		lease_dereference (&lease, MDL);
 }
@@ -918,8 +920,10 @@ void dhcpdecline (packet, ms_nulltp)
 
 	if (!ignorep)
 		log_info ("%s: %s", msgbuf, status);
-		
+
+#if defined(FAILOVER_PROTOCOL)
       out:
+#endif
 	if (options)
 		option_state_dereference (&options, MDL);
 	if (lease)
@@ -3153,6 +3157,7 @@ int find_lease (struct lease **lp,
 	struct data_string client_identifier;
 	struct hardware h;
 
+#if defined(FAILOVER_PROTOCOL)
 	/* Quick check to see if the peer has leases. */
 	if (peer_has_leases) {
 		struct pool *pool;
@@ -3168,6 +3173,7 @@ int find_lease (struct lease **lp,
 			}
 		}
 	}
+#endif /* FAILOVER_PROTOCOL */
 
 	if (packet -> raw -> ciaddr.s_addr) {
 		cip.len = 4;
@@ -3487,7 +3493,9 @@ int find_lease (struct lease **lp,
 	   is not active, and is not ours to reallocate, forget about it. */
 	if (ip_lease && (uid_lease || hw_lease) &&
 	    ip_lease -> binding_state != FTS_ACTIVE &&
+#if defined(FAILOVER_PROTOCOL)
 	    !lease_mine_to_reallocate (ip_lease) &&
+#endif
 	    packet -> packet_type == DHCPDISCOVER) {
 #if defined (DEBUG_FIND_LEASE)
 		log_info ("ip lease not ours to offer.");
diff --git a/server/dhcpd.c b/server/dhcpd.c
index c6084df3..3540e532 100644
--- a/server/dhcpd.c
+++ b/server/dhcpd.c
@@ -1342,8 +1342,8 @@ isc_result_t dhcp_io_shutdown (omapi_object_t *obj, void *foo)
 
 static isc_result_t dhcp_io_shutdown_countdown (void *vlp)
 {
-	dhcp_failover_state_t *state;
 #if defined (FAILOVER_PROTOCOL)
+	dhcp_failover_state_t *state;
 	int failover_connection_count = 0;
 #endif
 	struct timeval tv;
diff --git a/server/mdb.c b/server/mdb.c
index 43104b4d..42b3abc6 100644
--- a/server/mdb.c
+++ b/server/mdb.c
@@ -1515,6 +1515,7 @@ void make_binding_state_transition (struct lease *lease)
 	      case FTS_ABANDONED:
 	      case FTS_RESET:
 		lease -> next_binding_state = FTS_FREE;
+#if defined(FAILOVER_PROTOCOL)
 		/* If we are not in partner_down, leases don't go from
 		   EXPIRED to FREE on a timeout - only on an update.
 		   If we're in partner_down, they expire at mclt past
@@ -1524,6 +1525,7 @@ void make_binding_state_transition (struct lease *lease)
 			lease -> tsfp =
 			    (lease -> pool -> failover_peer -> me.stos +
 			     lease -> pool -> failover_peer -> mclt);
+#endif /* FAILOVER_PROTOCOL */
 		break;
 
 	      case FTS_FREE: