diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index dfb583ce5c..243a98c88f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -679,7 +679,7 @@ vulture:
   <<: *python_triggering_rules
   needs: []
   script:
-    - vulture --exclude "*ans.py,conftest.py,re_compile_checker.py,isctest" --ignore-names "after_servers_start,bootstrap,pytestmark" bin/tests/system/
+    - vulture --exclude "*ans.py,conftest.py,re_compile_checker.py,isctest" --ignore-names "after_servers_start,bootstrap,pytestmark,autouse_*" bin/tests/system/
 
 ci-variables:
   <<: *precheck_job
diff --git a/bin/tests/system/ans.py b/bin/tests/system/ans.py
new file mode 100644
index 0000000000..9dbdee11c1
--- /dev/null
+++ b/bin/tests/system/ans.py
@@ -0,0 +1,48 @@
+"""
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+SPDX-License-Identifier: MPL-2.0
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0.  If a copy of the MPL was not distributed with this
+file, you can obtain one at https://mozilla.org/MPL/2.0/.
+
+See the COPYRIGHT file distributed with this work for additional
+information regarding copyright ownership.
+"""
+
+"""
+This is a bare-bones DNS server that only serves data from zone files.  It is
+meant to be used as a replacement for full-blown named instances in system
+tests when a given server is only required to return zone-based data.
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+ BEWARE!  THIS SERVER DOES NOT NECESSARILY RETURN PROTOCOL-COMPLIANT ANSWERS!
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+See AsyncDnsServer._abort_if_*() methods in isctests/asyncserver.py for more
+details.  Use a regular named instance for anything non-trivial.
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+ DO NOT ADD CUSTOM LOGIC TO THIS FILE.  IT IS ONLY MEANT TO BE SYMLINKED INTO
+ansX/ SUBDIRECTORIES IN SYSTEM TESTS TO REDUCE THE AMOUNT OF BOILERPLATE CODE.
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+If you need to customize server behavior, implement it in a dedicated ans.py
+server in the system test at hand.  If an extension you are working on can be
+useful in other system tests, please consider opening a merge request extending
+isctest/asyncserver.py.
+"""
+
+from isctest.asyncserver import (
+    AsyncDnsServer,
+)
+
+
+def main() -> None:
+    server = AsyncDnsServer()
+    server.run()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/bin/tests/system/bailiwick/ans1/ans.py b/bin/tests/system/bailiwick/ans1/ans.py
new file mode 100644
index 0000000000..f0b152ac3d
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans1/ans.py
@@ -0,0 +1,68 @@
+"""
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+SPDX-License-Identifier: MPL-2.0
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0.  If a copy of the MPL was not distributed with this
+file, you can obtain one at https://mozilla.org/MPL/2.0/.
+
+See the COPYRIGHT file distributed with this work for additional
+information regarding copyright ownership.
+"""
+
+from typing import AsyncGenerator
+
+import dns.rdatatype
+import dns.rrset
+
+from isctest.asyncserver import (
+    DnsResponseSend,
+    QueryContext,
+    ResponseAction,
+)
+
+from bailiwick_ans import ResponseSpoofer, spoofing_server
+
+
+ATTACKER_IP = "10.53.0.3"
+TTL = 3600
+
+
+class SiblingNsSpoofer(ResponseSpoofer, mode="sibling-ns"):
+
+    qname = "trigger."
+
+    async def get_responses(
+        self, qctx: QueryContext
+    ) -> AsyncGenerator[ResponseAction, None]:
+        response = qctx.prepare_new_response(with_zone_data=False)
+
+        txt_rrset = dns.rrset.from_text(
+            qctx.qname,
+            TTL,
+            qctx.qclass,
+            dns.rdatatype.TXT,
+            '"spoofed answer with extra NS"',
+        )
+        response.answer.append(txt_rrset)
+
+        ns_rrset = dns.rrset.from_text(
+            "victim.", TTL, qctx.qclass, dns.rdatatype.NS, "ns.attacker."
+        )
+        response.authority.append(ns_rrset)
+
+        a_rrset = dns.rrset.from_text(
+            "ns.attacker.", TTL, qctx.qclass, dns.rdatatype.A, ATTACKER_IP
+        )
+        response.additional.append(a_rrset)
+
+        yield DnsResponseSend(response, authoritative=True)
+
+
+def main() -> None:
+    spoofing_server().run()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/bin/tests/system/bailiwick/ans1/root.db b/bin/tests/system/bailiwick/ans1/root.db
new file mode 100644
index 0000000000..64693727b6
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans1/root.db
@@ -0,0 +1,24 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+$ORIGIN .
+$TTL 3600
+. 			SOA	. . 0 0 0 0 3600
+.			NS	a.root-servers.nil.
+a.root-servers.nil.	A	10.53.0.1
+
+; queries should go here ... unless the attack succeeded
+victim.			NS	ns.victim.
+ns.victim.		A	10.53.0.2
+
+; no query should go here
+attacker.		NS	ns.attacker.
+ns.attacker.		A	10.53.0.3
diff --git a/bin/tests/system/bailiwick/ans2/ans.py b/bin/tests/system/bailiwick/ans2/ans.py
new file mode 100644
index 0000000000..1a9be3d931
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans2/ans.py
@@ -0,0 +1,110 @@
+"""
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+SPDX-License-Identifier: MPL-2.0
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0.  If a copy of the MPL was not distributed with this
+file, you can obtain one at https://mozilla.org/MPL/2.0/.
+
+See the COPYRIGHT file distributed with this work for additional
+information regarding copyright ownership.
+"""
+
+from typing import AsyncGenerator
+
+import dns.rdatatype
+import dns.rrset
+
+from isctest.asyncserver import (
+    DnsResponseSend,
+    QueryContext,
+    ResponseAction,
+)
+
+from bailiwick_ans import ResponseSpoofer, spoofing_server
+
+
+ATTACKER_IP = "10.53.0.3"
+TTL = 3600
+
+
+class UnsolicitedNsSpoofer(ResponseSpoofer, mode="unsolicited-ns"):
+
+    qname = "trigger.victim."
+
+    async def get_responses(
+        self, qctx: QueryContext
+    ) -> AsyncGenerator[ResponseAction, None]:
+        response = qctx.prepare_new_response(with_zone_data=False)
+
+        txt_rrset = dns.rrset.from_text(
+            qctx.qname,
+            TTL,
+            qctx.qclass,
+            dns.rdatatype.TXT,
+            '"spoofed answer with extra NS"',
+        )
+        response.answer.append(txt_rrset)
+
+        ns_rrset = dns.rrset.from_text(
+            "victim.", TTL, qctx.qclass, dns.rdatatype.NS, "ns.attacker."
+        )
+        response.authority.append(ns_rrset)
+
+        yield DnsResponseSend(response, authoritative=True)
+
+
+class ParentGlueSpoofer(ResponseSpoofer, mode="parent-glue"):
+
+    qname = "trigger.victim."
+
+    async def get_responses(
+        self, qctx: QueryContext
+    ) -> AsyncGenerator[ResponseAction, None]:
+        response = qctx.prepare_new_response(with_zone_data=False)
+
+        ns_rrset = dns.rrset.from_text(
+            "trigger.victim.", TTL, qctx.qclass, dns.rdatatype.NS, "ns.victim."
+        )
+        response.authority.append(ns_rrset)
+
+        glue_rrset = dns.rrset.from_text(
+            "ns.victim.", TTL, qctx.qclass, dns.rdatatype.A, ATTACKER_IP
+        )
+        response.additional.append(glue_rrset)
+
+        yield DnsResponseSend(response, authoritative=False)
+
+
+class DnameSpoofer(ResponseSpoofer, mode="dname"):
+
+    qname = "trigger.victim."
+
+    async def get_responses(
+        self, qctx: QueryContext
+    ) -> AsyncGenerator[ResponseAction, None]:
+        response = qctx.prepare_new_response(with_zone_data=False)
+
+        cname_rrset = dns.rrset.from_text(
+            qctx.qname,
+            TTL,
+            qctx.qclass,
+            dns.rdatatype.CNAME,
+            "trigger.attacker.",
+        )
+        dname_rrset = dns.rrset.from_text(
+            "victim.", TTL, qctx.qclass, dns.rdatatype.DNAME, "attacker."
+        )
+        response.answer.append(cname_rrset)
+        response.answer.append(dname_rrset)
+
+        yield DnsResponseSend(response, authoritative=True)
+
+
+def main() -> None:
+    spoofing_server().run()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/bin/tests/system/bailiwick/ans2/victim.db b/bin/tests/system/bailiwick/ans2/victim.db
new file mode 100644
index 0000000000..d5b4d258f4
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans2/victim.db
@@ -0,0 +1,17 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+$TTL 3600
+@ 			SOA	ns.victim. . 0 0 0 0 3600
+@			NS	ns
+ns			A	10.53.0.2
+prime			TXT	"this record is used for priming the cache of the targeted resolver"
+canary			TXT	"correct answer from the domain under attack"
diff --git a/bin/tests/system/bailiwick/ans3/ans.py b/bin/tests/system/bailiwick/ans3/ans.py
new file mode 120000
index 0000000000..2416f57e65
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans3/ans.py
@@ -0,0 +1 @@
+../../ans.py
\ No newline at end of file
diff --git a/bin/tests/system/bailiwick/ans3/attacker.db b/bin/tests/system/bailiwick/ans3/attacker.db
new file mode 100644
index 0000000000..e7474bbf30
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans3/attacker.db
@@ -0,0 +1,17 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+$TTL 3600
+@ 			SOA	ns.attacker. . 0 0 0 0 3600
+@			NS	ns
+ns			A	10.53.0.3
+only-if-hijacked	TXT	"this record only exists in the hijacked version of the zone"
+canary			TXT	"fake answer from attacker"
diff --git a/bin/tests/system/bailiwick/ans3/victim.db b/bin/tests/system/bailiwick/ans3/victim.db
new file mode 100644
index 0000000000..8f56c8d29d
--- /dev/null
+++ b/bin/tests/system/bailiwick/ans3/victim.db
@@ -0,0 +1,16 @@
+; Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+;
+; SPDX-License-Identifier: MPL-2.0
+;
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0.  If a copy of the MPL was not distributed with this
+; file, you can obtain one at https://mozilla.org/MPL/2.0/.
+;
+; See the COPYRIGHT file distributed with this work for additional
+; information regarding copyright ownership.
+
+$TTL 3600
+@ 			SOA	ns.attacker. . 0 0 0 0 3600
+@			NS	ns.attacker.
+only-if-hijacked	TXT	"this record only exists in the hijacked version of the zone"
+canary			TXT	"fake answer from attacker's auth"
diff --git a/bin/tests/system/bailiwick/bailiwick_ans.py b/bin/tests/system/bailiwick/bailiwick_ans.py
new file mode 100644
index 0000000000..28353a0a09
--- /dev/null
+++ b/bin/tests/system/bailiwick/bailiwick_ans.py
@@ -0,0 +1,102 @@
+"""
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+SPDX-License-Identifier: MPL-2.0
+
+This Source Code Form is subject to the terms of the Mozilla Public
+License, v. 2.0.  If a copy of the MPL was not distributed with this
+file, you can obtain one at https://mozilla.org/MPL/2.0/.
+
+See the COPYRIGHT file distributed with this work for additional
+information regarding copyright ownership.
+"""
+
+from typing import Dict, List, Optional, Type
+
+import abc
+
+import dns.name
+import dns.rcode
+import dns.rdatatype
+
+from isctest.asyncserver import (
+    ControlCommand,
+    ControllableAsyncDnsServer,
+    DnsProtocol,
+    QueryContext,
+    ResponseHandler,
+)
+
+
+class ResponseSpoofer(ResponseHandler, abc.ABC):
+
+    spoofers: Dict[str, Type["ResponseSpoofer"]] = {}
+
+    def __init_subclass__(cls, mode: str) -> None:
+        assert mode not in cls.spoofers
+        cls.spoofers[mode] = cls
+
+    @classmethod
+    def get_spoofer(cls, mode: str) -> Optional["ResponseSpoofer"]:
+        try:
+            return cls.spoofers[mode]()
+        except KeyError:
+            return None
+
+    @property
+    @abc.abstractmethod
+    def qname(self) -> str:
+        raise NotImplementedError
+
+    def match(self, qctx: QueryContext) -> bool:
+        return (
+            qctx.qname == dns.name.from_text(self.qname)
+            and qctx.qtype == dns.rdatatype.TXT
+            and qctx.protocol == DnsProtocol.UDP
+        )
+
+
+class SetSpoofingModeCommand(ControlCommand):
+    """
+    Select the ResponseSpoofer to use while handling queries from the resolver
+    under test (ns4).  This control command is used at the start of each test
+    function in tests_bailiwick.py.
+    """
+
+    control_subdomain = "set-spoofing-mode"
+
+    def __init__(self) -> None:
+        self._current_handler: Optional[ResponseSpoofer] = None
+
+    def handle(
+        self, args: List[str], server: ControllableAsyncDnsServer, qctx: QueryContext
+    ) -> Optional[str]:
+        if len(args) != 1:
+            qctx.response.set_rcode(dns.rcode.SERVFAIL)
+            return "invalid control command"
+
+        mode = args[0]
+
+        if mode == "none":
+            if self._current_handler:
+                server.uninstall_response_handler(self._current_handler)
+                self._current_handler = None
+            return "response spoofing disabled"
+
+        spoofer = ResponseSpoofer.get_spoofer(mode)
+        if not spoofer:
+            qctx.response.set_rcode(dns.rcode.SERVFAIL)
+            return f"unknown spoofing mode {mode}"
+
+        if self._current_handler:
+            server.uninstall_response_handler(self._current_handler)
+        server.install_response_handler(spoofer)
+        self._current_handler = spoofer
+
+        return f"response spoofing enabled (mode: {mode})"
+
+
+def spoofing_server() -> ControllableAsyncDnsServer:
+    server = ControllableAsyncDnsServer(default_rcode=dns.rcode.NOERROR)
+    server.install_control_command(SetSpoofingModeCommand())
+    return server
diff --git a/bin/tests/system/bailiwick/ns4/named.conf.j2 b/bin/tests/system/bailiwick/ns4/named.conf.j2
new file mode 100644
index 0000000000..449cad22e6
--- /dev/null
+++ b/bin/tests/system/bailiwick/ns4/named.conf.j2
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+options {
+	query-source address 10.53.0.4;
+	notify-source 10.53.0.4;
+	transfer-source 10.53.0.4;
+	port @PORT@;
+	pid-file "named.pid";
+	listen-on { 10.53.0.4; };
+	listen-on-v6 { none; };
+	recursion yes;
+	dnssec-validation no;
+	qname-minimization off;
+};
+
+controls {
+	inet 10.53.0.4 port @CONTROLPORT@ allow { any; } keys { rndc_key; };
+};
+
+include "../../_common/rndc.key";
+
+zone "." {
+	type hint;
+	file "../../_common/root.hint";
+};
diff --git a/bin/tests/system/bailiwick/tests_bailiwick.py b/bin/tests/system/bailiwick/tests_bailiwick.py
new file mode 100644
index 0000000000..7245c71bce
--- /dev/null
+++ b/bin/tests/system/bailiwick/tests_bailiwick.py
@@ -0,0 +1,119 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+from typing import Dict
+
+import time
+
+import dns.message
+
+import pytest
+
+# isctest.asyncserver requires dnspython >= 2.0.0
+pytest.importorskip("dns", minversion="2.0.0")
+
+import isctest
+from isctest.instance import NamedInstance
+
+
+@pytest.fixture(autouse=True)
+def autouse_flush_resolver_cache(servers: Dict[str, NamedInstance]) -> None:
+    servers["ns4"].rndc("flush")
+
+
+def set_spoofing_mode(ans1: str, ans2: str) -> None:
+    for ip, mode in (("10.53.0.1", ans1), ("10.53.0.2", ans2)):
+        msg = dns.message.make_query(f"{mode}.set-spoofing-mode._control.", "TXT")
+        res = isctest.query.tcp(msg, ip)
+        isctest.check.noerror(res)
+
+
+def prime_cache(ns4: NamedInstance) -> None:
+    msg = dns.message.make_query("prime.victim.", "TXT")
+    res = isctest.query.tcp(msg, ns4.ip)
+    isctest.check.noerror(res)
+
+    assert res.answer[0] == dns.rrset.from_text(
+        "prime.victim.",
+        0,
+        "IN",
+        "TXT",
+        '"this record is used for priming the cache of the targeted resolver"',
+    )
+
+
+def send_trigger_query(ns4: NamedInstance, qname: str) -> None:
+    msg = dns.message.make_query(qname, "TXT")
+    isctest.query.tcp(msg, ns4.ip)
+    # The contents of the resolver's response to the trigger query do not
+    # matter, so they are not checked in any way; what matters is whether the
+    # spoofed response succeeded in hijacking the "victim." domain, which is
+    # checked below.
+
+
+def check_domain_hijack(ns4: NamedInstance) -> None:
+    # Not necessary for triggering bugs, but useful for troubleshooting test
+    # behavior.
+    ns4.rndc("dumpdb -cache")
+
+    msg = dns.message.make_query("only-if-hijacked.victim.", "TXT")
+    res = isctest.query.tcp(msg, ns4.ip)
+    isctest.check.nxdomain(res)
+
+    msg = dns.message.make_query("canary.victim.", "TXT")
+    res = isctest.query.tcp(msg, ns4.ip)
+    isctest.check.noerror(res)
+
+    assert res.answer[0] == dns.rrset.from_text(
+        "canary.victim.",
+        0,
+        "IN",
+        "TXT",
+        '"correct answer from the domain under attack"',
+    )
+
+
+def test_bailiwick_sibling_ns_referral(servers: Dict[str, NamedInstance]) -> None:
+    set_spoofing_mode(ans1="sibling-ns", ans2="none")
+
+    ns4 = servers["ns4"]
+    send_trigger_query(ns4, "trigger.")
+    check_domain_hijack(ns4)
+
+
+def test_bailiwick_unsolicited_authority(servers: Dict[str, NamedInstance]) -> None:
+    set_spoofing_mode(ans1="none", ans2="unsolicited-ns")
+
+    ns4 = servers["ns4"]
+    prime_cache(ns4)
+    send_trigger_query(ns4, "trigger.victim.")
+    check_domain_hijack(ns4)
+
+
+def test_bailiwick_parent_glue(servers: Dict[str, NamedInstance]) -> None:
+    set_spoofing_mode(ans1="none", ans2="parent-glue")
+
+    ns4 = servers["ns4"]
+    prime_cache(ns4)
+    send_trigger_query(ns4, "trigger.victim.")
+
+    isctest.log.info("Waiting 61 seconds for the ns.victim. ADB entry to expire")
+    time.sleep(61)
+
+    check_domain_hijack(ns4)
+
+
+def test_bailiwick_spoofed_dname(servers: Dict[str, NamedInstance]) -> None:
+    set_spoofing_mode(ans1="none", ans2="dname")
+
+    ns4 = servers["ns4"]
+    send_trigger_query(ns4, "trigger.victim.")
+    check_domain_hijack(ns4)