Delay IPv6 client name lookups

src/FTL.h

@@ -138,6 +138,12 @@
 // Default: 30 (seconds)
 #define QPS_AVGLEN 30
 
+// How long should IPv6 client host name resolution be postponed?
+// This is done to ensure that the network table had time to catch up on new
+// clients in the network
+// Default: 2 x database.DBinterval (seconds) = 120 s
+#define DELAY_V6_RESOLUTION 2*config.database.DBinterval.v.ui
+
 // Use out own syscalls handling functions that will detect possible errors
 // and report accordingly in the log. This will make debugging FTL crash
 // caused by insufficient memory or by code bugs (not properly dealing

src/resolve.c

@@ -895,6 +895,21 @@ static void resolveClients(const bool onlynew, const bool force_refreshing)
 		if((ipaddr = getstr(ippos)) != NULL && strstr(ipaddr,":") != NULL)
 			IPv6 = true;
 
+		// If onlynew flag is set, we will only resolve new clients.
+		// However, if this is a IPv6 client, we postpone the resolution
+		// slightly to ensure the network table has had time to possibly
+		// correlate the IPv6 address via a related other address (e.g.,
+		// IPv4 address) though an identical MAC address.
+		if(onlynew && newflag && IPv6 && client->firstSeen + DELAY_V6_RESOLUTION > now)
+		{
+			log_debug(DEBUG_RESOLVER, "Postponing resolution of new client %s (IPv6) for at least %.0f more seconds",
+			          getstr(ippos), now - client->firstSeen + DELAY_V6_RESOLUTION);
+
+			unlock_shm();
+			skipped++;
+			continue;
+		}
+
 		unlock_shm();
 
 		// If we're in refreshing mode (onlynew == false), we skip clients if