DNS/1/security/cookies/CHANGESについて、ここに記述してください。 

4152.   [func]          Implement DNS COOKIE option.  This replaces the
                        experimental SIT option of BIND 9.10.  The following
                        named.conf directives are available: send-cookie,
                        cookie-secret, cookie-algorithm, nocookie-udp-size
                        and require-server-cookie.  The following dig options
                        are available: +[no]cookie[=value] and +[no]badcookie.
                        [RT #39928]

https://kb.isc.org/article/AA-01387/0/DNS-Cookies-in-BIND-9.10-and-9.11.html

By default, (new) dig will send requests with a DNS COOKIE option present.