diff --git a/client.c b/client.c
index c2af79c..899732f 100644
--- a/client.c
+++ b/client.c
@@ -902,6 +902,13 @@ process_cmd_add_server_or_peer(CMD_Request *msg, char *line)
   status = CPS_ParseNTPSourceAdd(line, &data);
   switch (status) {
     case CPS_Success:
+      /* Don't retry name resolving */
+      if (data.ip_addr.family == IPADDR_UNSPEC) {
+        Free(data.name);
+        fprintf(stderr, "Invalid host/IP address\n");
+        break;
+      }
+
       msg->data.ntp_source.port = htonl((unsigned long) data.port);
       UTI_IPHostToNetwork(&data.ip_addr, &msg->data.ntp_source.ip_addr);
       msg->data.ntp_source.minpoll = htonl(data.params.minpoll);
diff --git a/cmdparse.c b/cmdparse.c
index 668e08d..5dad262 100644
--- a/cmdparse.c
+++ b/cmdparse.c
@@ -33,6 +33,7 @@
 #include "sysincl.h"
 
 #include "cmdparse.h"
+#include "memory.h"
 #include "nameserv.h"
 
 #define MAXLEN 2047
@@ -66,6 +67,10 @@ CPS_ParseNTPSourceAdd(const char *line, CPS_NTP_Source *src)
     s = DNS_Name2IPAddress(hostname, &src->ip_addr);
     if (s == DNS_Success) {
       ok = 1;
+      src->name = NULL;
+    } else if (s == DNS_TryAgain) {
+      ok = 1;
+      src->ip_addr.family = IPADDR_UNSPEC;
     }
   }
 
@@ -160,6 +165,13 @@ CPS_ParseNTPSourceAdd(const char *line, CPS_NTP_Source *src)
     } while (!done);
   }
 
+  if (ok && src->ip_addr.family == IPADDR_UNSPEC) {
+    n = strlen(hostname);
+    src->name = MallocArray(char, n + 1);
+    strncpy(src->name, hostname, n);
+    src->name[n] = '\0';
+  }
+
   return result;
     
 }
diff --git a/cmdparse.h b/cmdparse.h
index 30fea49..7523d8e 100644
--- a/cmdparse.h
+++ b/cmdparse.h
@@ -49,6 +49,7 @@ typedef enum {
 
 typedef struct {
   IPAddr ip_addr;
+  char *name;
   unsigned short port;
   SourceParameters params;
 } CPS_NTP_Source;
diff --git a/conf.c b/conf.c
index 0f049b5..1556c2f 100644
--- a/conf.c
+++ b/conf.c
@@ -262,9 +262,7 @@ static int line_number;
 
 typedef struct {
   NTP_Source_Type type;
-  IPAddr ip_addr;
-  unsigned short port;
-  SourceParameters params;
+  CPS_NTP_Source params;
 } NTP_Source;
 
 #define MAX_NTP_SOURCES 64
@@ -355,23 +353,14 @@ CNF_ReadFile(const char *filename)
 static void
 parse_source(const char *line, NTP_Source_Type type)
 {
-  int i;
-  NTP_Source s;
   CPS_Status status;
-  CPS_NTP_Source params;
 
-  s.type = type;
-  status = CPS_ParseNTPSourceAdd(line, &params);
+  ntp_sources[n_ntp_sources].type = type;
+  status = CPS_ParseNTPSourceAdd(line, &ntp_sources[n_ntp_sources].params);
 
   switch (status) {
     case CPS_Success:
-      s.port = params.port;
-      s.ip_addr = params.ip_addr;
-      s.params = params.params;
-
-      i = n_ntp_sources++;
-      ntp_sources[i] = s;
-
+      n_ntp_sources++;
       break;
     case CPS_BadOption:
       LOG(LOGS_WARN, LOGF_Configure, "Unrecognized subcommand at line %d", line_number);
@@ -1191,11 +1180,16 @@ CNF_AddSources(void) {
   int i;
 
   for (i=0; i<n_ntp_sources; i++) {
-    server.ip_addr = ntp_sources[i].ip_addr;
-    memset(&server.local_ip_addr, 0, sizeof (server.local_ip_addr));
-    server.port = ntp_sources[i].port;
+    if (ntp_sources[i].params.ip_addr.family != IPADDR_UNSPEC) {
+      server.ip_addr = ntp_sources[i].params.ip_addr;
+      memset(&server.local_ip_addr, 0, sizeof (server.local_ip_addr));
+      server.port = ntp_sources[i].params.port;
 
-    NSR_AddSource(&server, ntp_sources[i].type, &ntp_sources[i].params);
+      NSR_AddSource(&server, ntp_sources[i].type, &ntp_sources[i].params.params);
+    } else {
+      NSR_AddUnresolvedSource(ntp_sources[i].params.name, ntp_sources[i].params.port,
+          ntp_sources[i].type, &ntp_sources[i].params.params);
+    }
   }
 
   return;
diff --git a/ntp_sources.c b/ntp_sources.c
index cc37435..b7151f2 100644
--- a/ntp_sources.c
+++ b/ntp_sources.c
@@ -37,6 +37,9 @@
 #include "util.h"
 #include "logging.h"
 #include "local.h"
+#include "memory.h"
+#include "nameserv.h"
+#include "sched.h"
 
 /* ================================================== */
 
@@ -60,6 +63,19 @@ static int n_sources;
 /* The largest number of sources we want to have stored in the hash table */
 #define MAX_SOURCES 64
 
+/* Source with unknown address (which may be resolved later) */
+struct UnresolvedSource {
+  char *name;
+  int port;
+  NTP_Source_Type type;
+  SourceParameters params;
+  struct UnresolvedSource *next;
+};
+
+static struct UnresolvedSource *unresolved_sources = NULL;
+static int resolving_interval = 0;
+static SCH_TimeoutID resolving_id;
+
 /* ================================================== */
 /* Forward prototypes */
 static void
@@ -203,6 +219,75 @@ NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type, SourceParam
 
 /* ================================================== */
 
+static void
+resolve_sources(void *arg)
+{
+  NTP_Remote_Address address;
+  struct UnresolvedSource *us, **i;
+  DNS_Status s;
+
+  memset(&address.local_ip_addr, 0, sizeof (address.local_ip_addr));
+
+  DNS_Reload();
+
+  for (i = &unresolved_sources; *i; ) {
+    us = *i;
+    s = DNS_Name2IPAddress(us->name, &address.ip_addr);
+    if (s == DNS_TryAgain) {
+      i = &(*i)->next;
+      continue;
+    } else if (s == DNS_Success) {
+      address.port = us->port;
+      NSR_AddSource(&address, us->type, &us->params);
+    } else {
+      LOG(LOGS_WARN, LOGF_NtpSources, "Invalid host %s", us->name);
+    }
+    
+    *i = us->next;
+
+    Free(us->name);
+    Free(us);
+  }
+
+  if (unresolved_sources) {
+    /* Try again later */
+    if (resolving_interval < 9)
+      resolving_interval++;
+    resolving_id = SCH_AddTimeoutByDelay(7 * (1 << resolving_interval), resolve_sources, NULL);
+  } else {
+    resolving_interval = 0;
+  }
+}
+
+/* ================================================== */
+
+/* Procedure to add a new server or peer source, but instead of an IP address
+   only a name is provided */
+void
+NSR_AddUnresolvedSource(char *name, int port, NTP_Source_Type type, SourceParameters *params)
+{
+  struct UnresolvedSource *us, **i;
+
+  us = MallocNew(struct UnresolvedSource);
+
+  us->name = name;
+  us->port = port;
+  us->type = type;
+  us->params = *params;
+  us->next = NULL;
+
+  for (i = &unresolved_sources; *i; i = &(*i)->next)
+    ;
+  *i = us;
+
+  if (!resolving_interval) {
+    resolving_interval = 2;
+    resolving_id = SCH_AddTimeoutByDelay(7 * (1 << resolving_interval), resolve_sources, NULL);
+  }
+}
+
+/* ================================================== */
+
 /* Procedure to remove a source.  We don't bother whether the port
    address is matched - we're only interested in removing a record for
    the right IP address.  Thus the caller can specify the port number
@@ -311,6 +396,13 @@ NSR_TakeSourcesOnline(IPAddr *mask, IPAddr *address)
     }
   }
 
+  if (resolving_interval) {
+    /* Try to resolve any unresolved sources now */
+    SCH_RemoveTimeout(resolving_id);
+    resolving_interval--;
+    resolve_sources(NULL);
+  }
+
   return any;
 }
 
@@ -472,6 +564,7 @@ void
 NSR_GetActivityReport(RPT_ActivityReport *report)
 {
   int i;
+  struct UnresolvedSource *us;
 
   report->online = 0;
   report->offline = 0;
@@ -484,6 +577,12 @@ NSR_GetActivityReport(RPT_ActivityReport *report)
                                     &report->burst_online, &report->burst_offline);
     }
   }
+
+  /* Add unresolved sources to offline count */
+  for (us = unresolved_sources; us; us = us->next) {
+    report->offline++;
+  }
+
   return;
 }
 
diff --git a/ntp_sources.h b/ntp_sources.h
index eaef8a8..d69ee0d 100644
--- a/ntp_sources.h
+++ b/ntp_sources.h
@@ -53,6 +53,11 @@ typedef enum {
 /* Procedure to add a new server or peer source. */
 extern NSR_Status NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type, SourceParameters *params);
 
+/* Procedure to add a new server or peer source with currently unknown address.
+   The name will be periodically resolved in exponentially increasing intervals
+   until it succeeds or fails with a non-temporary error. */
+extern void NSR_AddUnresolvedSource(char *name, int port, NTP_Source_Type type, SourceParameters *params);
+
 /* Procedure to remove a source */
 extern NSR_Status NSR_RemoveSource(NTP_Remote_Address *remote_addr);