diff --git a/ps-hosts-not-found.py b/ps-hosts-not-found.py
new file mode 100644
index 0000000..f7eb09d
--- /dev/null
+++ b/ps-hosts-not-found.py
@@ -0,0 +1,174 @@
+# ps-hosts-not-found - This module checks whether expected hosts are found in the Elasticsearch throughput/latency/trace
+#                    data the day before yesterday and compares it with
+#                    the expected hosts from the provided mesh configuration.
+#                    It queries Elasticsearch for specific test data (throughput/latency/trace)
+#                    within a 24-hour time range and verifies if the hosts are listed in the index.
+#                    The function identifies hosts that are expected (in the mesh configuration)
+#                    but not found in Elasticsearch.
+#
+#                    The process retrieves the hosts from the configuration, queries Elasticsearch
+#                    for the relevant test data, and counts the number of hosts not found.
+#                    In addition, the function can generate a plot comparing the number of hosts found
+#                    in the configuration versus those found in Elasticsearch. This information helps
+#                    maintain an accurate and up-to-date monitoring system by identifying discrepancies
+#                    between the expected and actual data.
+#                    TODO: Marian's API returns sites whose names do not exactly match those recorded in Elasticsearch. This directly affects the tags that users use.
+# Author: Yana Holoborodko
+# Copyright 2024
+import helpers as hp
+import warnings
+import time
+import datetime as dt
+import hashlib
+import pandas as pd
+from elasticsearch import Elasticsearch
+from elasticsearch.helpers import scan
+import psconfig.api
+import urllib3
+from alarms import alarms
+
+def query4Hosts(dateFrom, dateTo, testType):
+    query = {
+            "bool" : {
+              "must" : [
+                {
+                  "range" : {
+                    "timestamp" : {
+                      "gt" : dateFrom,
+                      "lte": dateTo
+                    }
+                  }
+                }
+              ]
+            }
+          }
+    aggregations = {
+        "unique_host_pairs": {
+            "composite": {
+                "size": 20000,
+                "sources": [
+                    {
+                        "src_host": {
+                            "terms": {
+                                "field": "src_host"
+                            }
+                        }
+                    },
+                    {
+                        "dest_host": {
+                            "terms": {
+                                "field": "dest_host"
+                            }
+                        }
+                    }
+                ]
+            }
+        }
+    }
+    aggrs = []
+    aggdata = hp.es.search(index=f'ps_{testType}', query=query, aggregations=aggregations)
+    for item in aggdata['aggregations']['unique_host_pairs']['buckets']:
+        aggrs.append(item['key']['src_host'])
+        aggrs.append(item['key']['dest_host'])
+    return aggrs
+
+def queryData(dateFrom, dateTo, test):
+    data = []
+    # query in portions since ES does not allow aggregations with more than 10000 bins
+    intv = int(hp.CalcMinutes4Period(dateFrom, dateTo)/60)
+    time_list = hp.GetTimeRanges(dateFrom, dateTo, intv)
+    for i in range(len(time_list)-1):
+        data.extend(query4Hosts(time_list[i], time_list[i+1], test))
+    return set(data)
+
+def check_tests_for_host(host, mesh_config):
+    """
+    Classifies the host as belonging to one of the three test groups (latency, trace and throughput).
+    """
+    try:
+        types = mesh_config.get_test_types(host)
+    except Exception:
+        return False, False
+    latency = any(test in ['latency', 'latencybg'] for test in types)
+    trace = 'trace' in types
+    throughput = any(test in ['throughput', 'rtt'] for test in types) # as rtt is now in ps_throughput
+    return host, latency, trace, throughput
+
+def create_hosts_tests_types_grid(hosts, mesh_config):
+    """
+    Creates a dataframe with a list of all hosts and whether
+    or not they are tested in each group(latency and trace).
+    """
+    host_test_type = pd.DataFrame({
+    'host': list(hosts),
+    'owd': False,
+    'trace': False,
+    'throughput': False
+    })
+    host_test_type = host_test_type['host'].apply(
+        lambda host: pd.Series(check_tests_for_host(host, mesh_config))
+    )
+    host_test_type.columns = ['host', 'owd', 'trace', 'throughput']
+    return host_test_type
+
+def check_data_difference_in_es(data_from, data_to, test_type, expected_hosts):
+    """
+    Checks whether all expected(mentioned in configurations) hosts
+    were found in the Elasticsearch, and returns the list of hosts which were omitted.
+    Can creates the plot for visualization of results.
+    """
+    data = queryData(data_from, data_to, test_type)
+    difference = expected_hosts.difference(data)
+    p = len(difference)/len(expected_hosts) * 100
+    return difference, round(p, 2)
+
+if __name__ == '__main__':
+    urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
+    warnings.filterwarnings("ignore", category=DeprecationWarning)
+    today_date = dt.date.today()
+    delta = today_date - dt.timedelta(days=2)
+    time_from = dt.time(0, 0)
+    time_to = dt.time(23, 59, 59)
+    m_from = dt.datetime.combine(delta, time_from).strftime('%Y-%m-%dT%H:%M:%S.000Z')
+    m_to = dt.datetime.combine(delta, time_to).strftime('%Y-%m-%dT%H:%M:%S.000Z')
+    mesh_url = "https://psconfig.aglt2.org/pub/config"
+    mesh_config = psconfig.api.PSConfig(mesh_url)
+    all_hosts = mesh_config.get_all_hosts()
+    ips = list(all_hosts)
+    test_types = ['owd', 'trace', 'throughput']
+    expected_tests_types = create_hosts_tests_types_grid(ips, mesh_config)
+    sites_mapping = {}
+    stats = {'percent_owd': None,
+            'percent_trace': None,
+            'percent_throughput': None,
+            'num_not_found_owd': None,
+            'num_not_found_trace': None,
+            'num_not_found_throughput': None,
+            'num_expected_owd': None,
+            'num_expected_trace': None,
+            'num_expected_throughput': None}
+    for test in test_types:
+        expected_hosts_test = set(expected_tests_types[expected_tests_types[test] == True]['host'].to_list())
+        diff, percent = check_data_difference_in_es(m_from, m_to, test, expected_hosts_test)
+        for host in diff:
+            site = mesh_config.get_site(host)
+            if site not in sites_mapping:
+                type_subset = dict()
+                sites_mapping[site] = type_subset
+            if test not in sites_mapping[site].keys():
+                sites_mapping[site][test] = set()
+            sites_mapping[site][test].add(host)
+        stats[f'percent_{test}'] = percent
+        stats[f'num_not_found_{test}'] = len(diff)
+        stats[f'num_expected_{test}'] = len(expected_hosts_test)
+    # print(f"Hosts expected but not found in the Elasticsearch ps-owd({stats['percent_owd']}% ({stats['num_not_found_owd']}/{stats['num_expected_owd']}) out of included to configurations not found)\nHosts expected but not found in the Elasticsearch ps-trace({stats['percent_trace']}% ({stats['num_not_found_trace']}/{stats['num_expected_trace']}) out of included to configurations not found)\nHosts expected but not found in the Elasticsearch ps-owd({stats['percent_throughput']}% ({stats['num_not_found_throughput']}/{stats['num_expected_throughput']}) out of included to configurations not found)\n")
+    for s in sites_mapping.keys():
+        alarmOnSite = alarms('Networking', 'Sites', f"hosts not found")
+        doc = {'from': m_from,
+               'to': m_to,
+               'site': s,
+               'hosts': sites_mapping[s]}
+        toHash = ','.join([s, str(sites_mapping[s]), m_from, m_to, test])
+        doc['alarm_id'] = hashlib.sha224(toHash.encode('utf-8')).hexdigest()
+        alarmOnSite.addAlarm(body='not found in the Elasticsearch', tags=[s], source=doc)
+        # print(f"Hosts expected but not found in the Elasticsearch\n{s}\n{doc['hosts']}\n")
diff --git a/ps-hosts-not-found.sh b/ps-hosts-not-found.sh
new file mode 100644
index 0000000..82e250e
--- /dev/null
+++ b/ps-hosts-not-found.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+date
+python ps-hosts-not-found.py
+rc=$?; if [[ $rc != 0 ]]; then 
+    echo "problem running hosts not found. Exiting."
+    exit $rc
+fi