gh-160227: Add 192.88.99.2/32 (RFC 6751) to ipaddress IPv4 private networks

IANA's IPv4 Special-Purpose Address Registry lists 192.88.99.2/32
(6a44-relay anycast address, RFC 6751) as not globally reachable. The
row was added to the registry on 2025-06-26, after the IPv4 list was
last updated in gh-113171.

Author: gggg5151

Lib/ipaddress.py

@@ -1637,6 +1637,8 @@ class _IPv4Constants:
         IPv4Network('192.0.0.0/24'),
         IPv4Network('192.0.0.170/31'),
         IPv4Network('192.0.2.0/24'),
+        # RFC 6751: https://www.rfc-editor.org/rfc/rfc6751.html
+        IPv4Network('192.88.99.2/32'),
         IPv4Network('192.168.0.0/16'),
         IPv4Network('198.18.0.0/15'),
         IPv4Network('198.51.100.0/24'),

Lib/test/test_ipaddress.py

@@ -2409,6 +2409,9 @@ def testReservedIpv4(self):
         self.assertTrue(ipaddress.ip_address('192.0.0.9').is_global)
         self.assertTrue(ipaddress.ip_address('192.0.0.10').is_global)
         self.assertFalse(ipaddress.ip_address('192.0.0.255').is_global)
+        # gh-160227: 6a44-relay anycast address (RFC 6751)
+        self.assertFalse(ipaddress.ip_address('192.88.99.2').is_global)
+        self.assertTrue(ipaddress.ip_address('192.88.99.2').is_private)
 
         self.assertEqual(True,
                          ipaddress.ip_address('169.254.100.200').is_link_local)

Misc/NEWS.d/next/Library/2026-10-22-08-50-54.gh-issue-160227.Zq7mRb.rst

@@ -0,0 +1,3 @@
+Fix :attr:`ipaddress.IPv4Address.is_global` and
+:attr:`~ipaddress.IPv4Address.is_private` for ``192.88.99.2``, the 6a44-relay
+anycast address (:rfc:`6751`), which IANA lists as not globally reachable.