diff --git a/CHANGELOG b/CHANGELOG
index 92013ce..c36017a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -19,6 +19,7 @@
 - fix "nosymlink" option handling and add desription to man page.
 - fix don't fail on empty master map.
 - if there's no "automount" entry in nsswitch.conf use "files" source.
+- add LDAP schema discovery if no schema is configured.
 
 18/06/2007 autofs-5.0.2
 -----------------------
diff --git a/include/defaults.h b/include/defaults.h
index ef58467..9aec11a 100644
--- a/include/defaults.h
+++ b/include/defaults.h
@@ -43,11 +43,8 @@ unsigned int defaults_get_timeout(void);
 unsigned int defaults_get_browse_mode(void);
 unsigned int defaults_get_logging(void);
 const char *defaults_get_ldap_server(void);
-const char *defaults_get_map_obj_class(void);
-const char *defaults_get_entry_obj_class(void);
-const char *defaults_get_map_attr(void);
-const char *defaults_get_entry_attr(void);
-const char *defaults_get_value_attr(void);
+struct ldap_schema *defaults_get_default_schema(void);
+struct ldap_schema *defaults_get_schema(void);
 unsigned int defaults_get_append_options(void);
 const char *defaults_get_auth_conf_file(void);
 
diff --git a/include/lookup_ldap.h b/include/lookup_ldap.h
index 0a9deca..1378b9e 100644
--- a/include/lookup_ldap.h
+++ b/include/lookup_ldap.h
@@ -10,6 +10,14 @@
 #include <krb5.h>
 #endif
 
+struct ldap_schema {
+	char *map_class;
+	char *map_attr;
+	char *entry_class;
+	char *entry_attr;
+	char *value_attr;
+};
+
 struct lookup_context {
 	char *mapname;
 
@@ -22,11 +30,7 @@ struct lookup_context {
 	int version;
 
 	/* LDAP lookup configuration */
-	char *map_obj_class;
-	char *entry_obj_class;
-	char *map_attr;
-	char *entry_attr;
-	char *value_attr;
+	struct ldap_schema *schema;
 
 	/* TLS and SASL authentication information */
 	char        *auth_conf;
diff --git a/lib/defaults.c b/lib/defaults.c
index 4b4acba..b146f13 100644
--- a/lib/defaults.c
+++ b/lib/defaults.c
@@ -18,6 +18,7 @@
 #include <string.h>
 
 #include "defaults.h"
+#include "lookup_ldap.h"
 #include "log.h"
 
 #define DEFAULTS_CONFIG_FILE		AUTOFS_CONF_DIR "/autofs"
@@ -41,16 +42,8 @@
 #define ENV_AUTH_CONF_FILE		"AUTH_CONF_FILE"
 
 static const char *default_master_map_name = DEFAULT_MASTER_MAP_NAME;
-
-static const char *default_ldap_server		= DEFAULT_LDAP_SERVER;
-
-static const char *default_map_obj_class	= DEFAULT_MAP_OBJ_CLASS;
-static const char *default_entry_obj_class	= DEFAULT_ENTRY_OBJ_CLASS;
-static const char *default_map_attr		= DEFAULT_MAP_ATTR;
-static const char *default_entry_attr		= DEFAULT_ENTRY_ATTR;
-static const char *default_value_attr		= DEFAULT_VALUE_ATTR;
-
-static const char *default_auth_conf_file = DEFAULT_AUTH_CONF_FILE;
+static const char *default_ldap_server	   = DEFAULT_LDAP_SERVER;
+static const char *default_auth_conf_file  = DEFAULT_AUTH_CONF_FILE;
 
 static char *get_env_string(const char *name)
 {
@@ -285,59 +278,120 @@ const char *defaults_get_ldap_server(void)
 	return (const char *) server;
 }
 
-const char *defaults_get_map_obj_class(void)
+struct ldap_schema *defaults_get_default_schema(void)
 {
-	char *moc;
+	struct ldap_schema *schema;
+	char *mc, *ma, *ec, *ea, *va;
 
-	moc = get_env_string(ENV_NAME_MAP_OBJ_CLASS);
-	if (!moc)
-		return strdup(default_map_obj_class);
+	mc = strdup(DEFAULT_MAP_OBJ_CLASS);
+	if (!mc)
+		return NULL;
 
-	return (const char *) moc;
-}
+	ma = strdup(DEFAULT_MAP_ATTR);
+	if (!ma) {
+		free(mc);
+		return NULL;
+	}
 
-const char *defaults_get_entry_obj_class(void)
-{
-	char *eoc;
+	ec = strdup(DEFAULT_ENTRY_OBJ_CLASS);
+	if (!ec) {
+		free(mc);
+		free(ma);
+		return NULL;
+	}
 
-	eoc = get_env_string(ENV_NAME_ENTRY_OBJ_CLASS);
-	if (!eoc)
-		return strdup(default_entry_obj_class);
+	ea = strdup(DEFAULT_ENTRY_ATTR);
+	if (!ea) {
+		free(mc);
+		free(ma);
+		free(ec);
+		return NULL;
+	}
 
-	return (const char *) eoc;
-}
+	va = strdup(DEFAULT_VALUE_ATTR);
+	if (!va) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		return NULL;
+	}
 
-const char *defaults_get_map_attr(void)
-{
-	char *ma;
+	schema = malloc(sizeof(struct ldap_schema));
+	if (!schema) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		free(va);
+		return NULL;
+	}
 
-	ma = get_env_string(ENV_NAME_MAP_ATTR);
-	if (!ma)
-		return strdup(default_map_attr);
+	schema->map_class = mc;
+	schema->map_attr = ma;
+	schema->entry_class = ec;
+	schema->entry_attr = ea;
+	schema->value_attr = va;
 
-	return (const char *) ma;
+	return schema;
 }
 
-const char *defaults_get_entry_attr(void)
+struct ldap_schema *defaults_get_schema(void)
 {
-	char *ea;
+	struct ldap_schema *schema;
+	char *mc, *ma, *ec, *ea, *va;
 
-	ea = get_env_string(ENV_NAME_ENTRY_ATTR);
-	if (!ea)
-		return strdup(default_entry_attr);
+	mc = get_env_string(ENV_NAME_MAP_OBJ_CLASS);
+	if (!mc)
+		return NULL;
 
-	return (const char *) ea;
-}
+	ma = get_env_string(ENV_NAME_MAP_ATTR);
+	if (!ma) {
+		free(mc);
+		return NULL;
+	}
 
-const char *defaults_get_value_attr(void)
-{
-	char *va;
+	ec = get_env_string(ENV_NAME_ENTRY_OBJ_CLASS);
+	if (!ec) {
+		free(mc);
+		free(ma);
+		return NULL;
+	}
+
+	ea = get_env_string(ENV_NAME_ENTRY_ATTR);
+	if (!ea) {
+		free(mc);
+		free(ma);
+		free(ec);
+		return NULL;
+	}
 
 	va = get_env_string(ENV_NAME_VALUE_ATTR);
-	if (!va)
-		return strdup(default_value_attr);
+	if (!va) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		return NULL;
+	}
+
+	schema = malloc(sizeof(struct ldap_schema));
+	if (!schema) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		free(va);
+		return NULL;
+	}
+
+	schema->map_class = mc;
+	schema->map_attr = ma;
+	schema->entry_class = ec;
+	schema->entry_attr = ea;
+	schema->value_attr = va;
 
-	return (const char *) va;
+	return schema;
 }
 
 unsigned int defaults_get_append_options(void)
diff --git a/man/auto.master.5.in b/man/auto.master.5.in
index 69c796e..249c9a7 100644
--- a/man/auto.master.5.in
+++ b/man/auto.master.5.in
@@ -191,17 +191,25 @@ The old style
 is also understood. Alternatively, the type can be obtained from the Name Service Switch
 configuration, in which case the map name alone must be given.
 .P
-The default LDAP schema is the NIS schema described in RFC 2307.
-Entries in the nisMap schema are \fBnisObject\fP objects in
+If no schema is set in the autofs configuration then autofs will check
+each of the commonly used schema for a valid entry and if one is found
+it will used for subsequent lookups.
+.P
+There are three common schemas in use:
+.TP
+.I nisMap
+Entries in the \fBnisMap\fP schema are \fBnisObject\fP objects in
 the specified subtree, where the \fBcn\fP attribute is the key
 (the wildcard key is "/"), and the \fBnisMapEntry\fP attribute
 contains the information used by the automounter.
-.P
-Entries in the automountMap schema are \fBautomount\fP objects in
-the specified subtree, where the \fBcn\fP or \fBautomountKey\fP attribute
-(depending on local usage) is the key (the wildcard key is "/"), and the
-\fBautomountInformation\fP attribute contains the information used by the
-automounter.
+.TP
+.I automountMap
+The \fBautomountMap\fP schema has two variations that differ in the attribute
+used for the map key. Entries in the automountMap schema are \fBautomount\fP
+objects in the specified subtree, where the \fBcn\fP or \fBautomountKey\fP
+attribute (depending on local usage) is the key (the wildcard key is "/"),
+and the \fBautomountInformation\fP attribute contains the information used
+by the automounter. Note that the \fBcn\fP attribute is case insensitive.
 .P
 The object classes and attributes used for accessing automount maps in
 LDAP can be changed by setting entries in the autofs configuration
@@ -209,61 +217,44 @@ located in
 .nh
 .BR @@autofsconfdir@@/autofs .
 .hy
+.TP
+.B NOTE:
+If a schema is given in the configuration then all the schema configuration
+values must be set, any partial schema specification will be ignored.
 .P
 The configuration settings available are:
 .TP
-\fBMAP_OBJECT_CLASS\fP
-The map object class. Its Default value is "nisMap". In the
-.nh
-automountMap
-.hy
-schema this corresponds to the class
-.nh
-.BR automountMap .
-.hy
+.B MAP_OBJECT_CLASS
+The map object class. In the \fBnisMap\fP schema this corresponds to the class
+\fBnisMap\fP and in the \fBautomountMap\fP schema it corresponds to the class
+\fBautomountMap\fP.
 .TP
 .B ENTRY_OBJECT_CLASS
-The map entry object class. Its default value is \fBnisObject\fP.
-In the automountMap schema this corresponds to the class
-.nh
-.BR automount .
-.hy
+The map entry object class. In the \fBnisMap\fP schema this corresponds
+to the class \fBnisObject\fP and in the \fBautomountMap\fP schema it
+corresponds to the class \fBautomount\fP.
 .TP
 .B MAP_ATTRIBUTE
 The attribute used to identify the name of the map to which this
-entry belongs. Its default value is
-.nh
-.BR nisMapName .
-.hy
-In the
-.nh
-automountMap
-.hy
-schema this corresponds to the attributes \fBou\fP or
-.nh
-.BR automountMapName .
-.hy
+entry belongs.  In the \fBnisMap\fP schema this corresponds to the attribute
+\fBnisMapName\fP and in the \fBautomountMap\fP schema it corresponds to the
+attribute \fBou\fP or \fBautomountMapName\fP.
 .TP
 .B ENTRY_ATTRIBUTE
-The attribute used to identify a map key. Its default value is
-In the
-.nh
-automountMap
-.hy
-schema this corresponds to the attribute
-.nh
-.BR automountKey .
-.hy
+The attribute used to identify a map key. In the \fBnisMap\fP schema this
+corresponds to the attribute \fBcn\fP and in the \fBautomountMap\fP schema
+it corresponds to the attribute \fBautomountKey\fP.
 .TP
 .B VALUE_ATTRIBUTE
-The attribute used to identify the value of the map entry. Its default
-value is
-.nh
-.BR BnisMapEntry .
-.hy
-In the automountMap schema this corresponds to the attribute
-.nh
-.BR automountInformation .
+The attribute used to identify the value of the map entry. In the \fBnisMap\fP
+schema this corresponds to the attribute \fBnisMapEntry\fP and in the \fBautomountMap\fP
+schema it corresponds to the attribute \fBautomountInformation\fP.
+.TP
+.B NOTE:
+It is essential that entries use class and attribute in a consistent
+manner for correct operation of autofs. For example mixing \fBcn\fP and
+\fBautomountKey\fP attributes in \fBautomount\fP schema map entries won't
+work as expected.
 .SH LDAP AUTHENTICATION, ENCRYPTED AND CERTIFIED CONNECTIONS
 LDAP authenticated binds, TLS encrypted connections and certification
 may be used by setting appropriate values in the autofs authentication
diff --git a/man/automount.8 b/man/automount.8
index fc1846a..da67a5c 100644
--- a/man/automount.8
+++ b/man/automount.8
@@ -102,6 +102,8 @@ started they will be recoverd unless they are no longer present in
 the map in which case they need to umounted manually.
 .SH "SEE ALSO"
 .BR autofs (5),
+.BR autofs (8),
+.BR auto.master (5),
 .BR mount (8).
 .SH BUGS
 Don't know, I've fixed everything I know about.
diff --git a/modules/lookup_ldap.c b/modules/lookup_ldap.c
index a412797..d5e666b 100644
--- a/modules/lookup_ldap.c
+++ b/modules/lookup_ldap.c
@@ -42,6 +42,13 @@
 
 int lookup_version = AUTOFS_LOOKUP_VERSION;	/* Required by protocol */
 
+static struct ldap_schema common_schema[] = {
+	{"nisMap", "nisMapName", "nisObject", "cn", "nisMapEntry"},
+	{"automountMap", "ou", "automount", "cn", "automountInformation"},
+	{"automountMap", "automountMapName", "automount", "automountKey", "automountInformation"},
+};
+static unsigned int common_schema_count = sizeof(common_schema)/sizeof(struct ldap_schema);
+
 int bind_ldap_anonymous(LDAP *ldap, struct lookup_context *ctxt)
 {
 	int rv;
@@ -738,54 +745,15 @@ done:
 	return 1;
 }
 
-static int get_default_schema(struct lookup_context *ctxt)
-{
-	ctxt->map_obj_class = (char *) defaults_get_map_obj_class();
-	if (!ctxt->map_obj_class)
-		return 0;
-
-	ctxt->entry_obj_class = (char *) defaults_get_entry_obj_class();
-	if (!ctxt->entry_obj_class)
-		goto free_moc;
-
-	ctxt->map_attr = (char *) defaults_get_map_attr();
-	if (!ctxt->map_attr)
-		goto free_eoc;
-
-	ctxt->entry_attr = (char *) defaults_get_entry_attr();
-	if (!ctxt->entry_attr)
-		goto free_ma;
-
-	ctxt->value_attr = (char *) defaults_get_value_attr();
-	if (!ctxt->value_attr)
-		goto free_ea;
-
-	return 1;
-
-free_ea:
-	free(ctxt->entry_attr);
-free_ma:
-	free(ctxt->map_attr);
-free_eoc:
-	free(ctxt->entry_obj_class);
-free_moc:
-	free(ctxt->map_obj_class);
-
-	ctxt->map_obj_class = NULL;
-	ctxt->entry_obj_class = NULL;
-	ctxt->map_attr = NULL;
-	ctxt->entry_attr = NULL;
-
-	return 0;
-}
-
 static void free_context(struct lookup_context *ctxt)
 {
-	if (ctxt->map_obj_class) {
-		free(ctxt->map_obj_class);
-		free(ctxt->entry_obj_class);
-		free(ctxt->map_attr);
-		free(ctxt->entry_attr);
+	if (ctxt->schema) {
+		free(ctxt->schema->map_class);
+		free(ctxt->schema->map_attr);
+		free(ctxt->schema->entry_class);
+		free(ctxt->schema->entry_attr);
+		free(ctxt->schema->value_attr);
+		free(ctxt->schema);
 	}
 	if (ctxt->auth_conf)
 		free(ctxt->auth_conf);
@@ -808,19 +776,15 @@ static void free_context(struct lookup_context *ctxt)
 	return;
 }
 
-static int get_query_dn(LDAP *ldap, struct lookup_context *ctxt)
+static int get_query_dn(LDAP *ldap, struct lookup_context *ctxt, const char *class, const char *key)
 {
 	char buf[PARSE_MAX_BUF];
 	char *query, *dn;
 	LDAPMessage *result, *e;
-	char *class, *key;
 	char *attrs[2];
 	int scope;
 	int rv, l;
 
-	class = ctxt->map_obj_class;
-	key = ctxt->map_attr;
-
 	attrs[0] = LDAP_NO_ATTRS;
 	attrs[1] = NULL;
 
@@ -890,6 +854,90 @@ static int get_query_dn(LDAP *ldap, struct lookup_context *ctxt)
 	return 1;
 }
 
+static struct ldap_schema *alloc_common_schema(struct ldap_schema *s)
+{
+	struct ldap_schema *schema;
+	char *mc, *ma, *ec, *ea, *va;
+
+	mc = strdup(s->map_class);
+	if (!mc)
+		return NULL;
+
+	ma = strdup(s->map_attr);
+	if (!ma) {
+		free(mc);
+		return NULL;
+	}
+
+	ec = strdup(s->entry_class);
+	if (!ec) {
+		free(mc);
+		free(ma);
+		return NULL;
+	}
+
+	ea = strdup(s->entry_attr);
+	if (!ea) {
+		free(mc);
+		free(ma);
+		free(ec);
+		return NULL;
+	}
+
+	va = strdup(s->value_attr);
+	if (!va) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		return NULL;
+	}
+
+	schema = malloc(sizeof(struct ldap_schema));
+	if (!schema) {
+		free(mc);
+		free(ma);
+		free(ec);
+		free(ea);
+		free(va);
+		return NULL;
+	}
+
+	schema->map_class = mc;
+	schema->map_attr = ma;
+	schema->entry_class = ec;
+	schema->entry_attr = ea;
+	schema->value_attr = va;
+
+	return schema;
+}
+
+static int find_query_dn(LDAP *ldap, struct lookup_context *ctxt)
+{
+	struct ldap_schema *schema;
+	unsigned int i;
+
+	if (ctxt->schema)
+		return 0;
+
+	for (i = 0; i < common_schema_count; i++) {
+		const char *class = common_schema[i].map_class;
+		const char *key = common_schema[i].map_attr;
+		if (get_query_dn(ldap, ctxt, class, key)) {
+			schema = alloc_common_schema(&common_schema[i]);
+			if (!schema) {
+				error(LOGOPT_ANY,
+				      MODPREFIX "failed to allocate schema");
+				return 0;
+			}
+			ctxt->schema = schema;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * This initializes a context (persistent non-global data) for queries to
  * this module.  Return zero if we succeed.
@@ -926,13 +974,6 @@ int lookup_init(const char *mapfmt, int argc, const char *const *argv, void **co
 		return 1;
 	}
 
-	/* Get default schema for queries */
-	if (!get_default_schema(ctxt)) {
-		error(LOGOPT_ANY, MODPREFIX "cannot set default schema");
-		free_context(ctxt);
-		return 1;
-	}
-
 #ifdef WITH_SASL
 	/*
 	 * Determine which authentication mechanism to use.  We sanity-
@@ -954,13 +995,22 @@ int lookup_init(const char *mapfmt, int argc, const char *const *argv, void **co
 		return 1;
 	}
 
-	ret = get_query_dn(ldap, ctxt);
-	unbind_ldap_connection(ldap, ctxt);
-	if (!ret) {
-		error(LOGOPT_ANY, MODPREFIX "failed to get query dn");
-		free_context(ctxt);
-		return 1;
+	/*
+	 * Get default schema for queries.
+	 * If the schema isn't defined in the configuration then check for
+	 * presence of a map dn in the common schemas.
+	 */
+	ctxt->schema = defaults_get_schema();
+	if (!ctxt->schema) {
+		if (!find_query_dn(ldap, ctxt)) {
+			unbind_ldap_connection(ldap, ctxt);
+			error(LOGOPT_ANY,
+			      MODPREFIX "failed to find valid query dn");
+			free_context(ctxt);
+			return 1;
+		}
 	}
+	unbind_ldap_connection(ldap, ctxt);
 
 	/* Open the parser, if we can. */
 	ctxt->parse = open_parse(mapfmt, MODPREFIX, argc - 1, argv + 1);
@@ -990,9 +1040,9 @@ int lookup_read_master(struct master *master, time_t age, void *context)
 	int scope = LDAP_SCOPE_SUBTREE;
 	LDAP *ldap;
 
-	class = ctxt->entry_obj_class;
-	entry = ctxt->entry_attr;
-	info = ctxt->value_attr;
+	class = ctxt->schema->entry_class;
+	entry = ctxt->schema->entry_attr;
+	info = ctxt->schema->value_attr;
 
 	attrs[0] = entry;
 	attrs[1] = info;
@@ -1141,9 +1191,9 @@ static int read_one_map(struct autofs_point *ap,
 
 	mc = source->mc;
 
-	class = ctxt->entry_obj_class;
-	entry = ctxt->entry_attr;
-	info = ctxt->value_attr;
+	class = ctxt->schema->entry_class;
+	entry = ctxt->schema->entry_attr;
+	info = ctxt->schema->value_attr;
 
 	attrs[0] = entry;
 	attrs[1] = info;
@@ -1438,9 +1488,9 @@ static int lookup_one(struct autofs_point *ap,
 		return CHE_FAIL;
 	}
 
-	class = ctxt->entry_obj_class;
-	entry = ctxt->entry_attr;
-	info = ctxt->value_attr;
+	class = ctxt->schema->entry_class;
+	entry = ctxt->schema->entry_attr;
+	info = ctxt->schema->value_attr;
 
 	attrs[0] = entry;
 	attrs[1] = info;