我正在玩NSLOOKUP试图了解recursionDNS查找。 我正在查找一个虚假的主机名，我似乎得到相同的结果，无论我启用或禁用recursion。
recursion：
nslookup Default Server: UnKnown Address: ::1 > set recurse > set debug > nytimes Server: UnKnown Address: ::1 ------------ Got answer: HEADER: opcode = QUERY, id = 2, rcode = NXDOMAIN header flags: response, auth. answer, want recursion, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.intranet.contoso.com, type = A, class = IN AUTHORITY RECORDS: -> intranet.contoso.com ttl = 3600 (1 hour) primary name server = DNSSERVER.intranet.contoso.com responsible mail addr = hostmaster.intranet.contoso.com serial = 10301 refresh = 900 (15 mins) retry = 600 (10 mins) expire = 86400 (1 day) default TTL = 3600 (1 hour) ------------ ------------ Got answer: HEADER: opcode = QUERY, id = 3, rcode = NXDOMAIN header flags: response, auth. answer, want recursion, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.intranet.contoso.com, type = AAAA, class = IN AUTHORITY RECORDS: -> intranet.contoso.com ttl = 3600 (1 hour) primary name server = DNSSERVER.intranet.contoso.com responsible mail addr = hostmaster.intranet.contoso.com serial = 10301 refresh = 900 (15 mins) retry = 600 (10 mins) expire = 86400 (1 day) default TTL = 3600 (1 hour) ------------ ------------ Got answer: HEADER: opcode = QUERY, id = 4, rcode = NOERROR header flags: response, want recursion, recursion avail. questions = 1, answers = 1, authority records = 0, additional = 0 QUESTIONS: nytimes.contoso.com, type = A, class = IN ANSWERS: -> nytimes.contoso.com internet address = 74.125.226.195 ttl = 1800 (30 mins) ------------ Non-authoritative answer: ------------ Got answer: HEADER: opcode = QUERY, id = 5, rcode = NOERROR header flags: response, want recursion, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.contoso.com, type = AAAA, class = IN AUTHORITY RECORDS: -> contoso.com ttl = 900 (15 mins) primary name server = dns01.gpn.register.com responsible mail addr = partnersupport.register.com serial = 2002050701 refresh = 10800 (3 hours) retry = 3600 (1 hour) expire = 604800 (7 days) default TTL = 3600 (1 hour) ------------ Name: nytimes.contoso.com Address: 74.125.226.195 > 没有recursion：
nslookup Default Server: UnKnown Address: ::1 > set norecurse > set debug > nytimes Server: UnKnown Address: ::1 ------------ Got answer: HEADER: opcode = QUERY, id = 2, rcode = NXDOMAIN header flags: response, auth. answer, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.intranet.contoso.com, type = A, class = IN AUTHORITY RECORDS: -> intranet.contoso.com ttl = 3600 (1 hour) primary name server = DNSSERVER.intranet.contoso.com responsible mail addr = hostmaster.intranet.contoso.com serial = 10301 refresh = 900 (15 mins) retry = 600 (10 mins) expire = 86400 (1 day) default TTL = 3600 (1 hour) ------------ ------------ Got answer: HEADER: opcode = QUERY, id = 3, rcode = NXDOMAIN header flags: response, auth. answer, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.intranet.contoso.com, type = AAAA, class = IN AUTHORITY RECORDS: -> intranet.contoso.com ttl = 3600 (1 hour) primary name server = DNSSERVER.intranet.contoso.com responsible mail addr = hostmaster.intranet.contoso.com serial = 10301 refresh = 900 (15 mins) retry = 600 (10 mins) expire = 86400 (1 day) default TTL = 3600 (1 hour) ------------ ------------ Got answer: HEADER: opcode = QUERY, id = 4, rcode = NOERROR header flags: response, recursion avail. questions = 1, answers = 1, authority records = 0, additional = 0 QUESTIONS: nytimes.contoso.com, type = A, class = IN ANSWERS: -> nytimes.contoso.com internet address = 74.125.226.195 ttl = 1526 (25 mins 26 secs) ------------ Non-authoritative answer: ------------ Got answer: HEADER: opcode = QUERY, id = 5, rcode = NOERROR header flags: response, recursion avail. questions = 1, answers = 0, authority records = 1, additional = 0 QUESTIONS: nytimes.contoso.com, type = AAAA, class = IN AUTHORITY RECORDS: -> contoso.com ttl = 626 (10 mins 26 secs) primary name server = dns01.gpn.register.com responsible mail addr = partnersupport.register.com serial = 2002050701 refresh = 10800 (3 hours) retry = 3600 (1 hour) expire = 604800 (7 days) default TTL = 3600 (1 hour) ------------ Name: nytimes.contoso.com Address: 74.125.226.195 >
它看起来像使用recursion，即使我把它设置为closures。 有趣的是，如果我查找指定4.2.2.2的伪造主机名作为DNS服务器，那么recursion设置确实生效。 任何人都知道这是为什么发生？
顺便说一句我清理主机名
除了愿意为您执行recursion之外，服务器在设置了norecurse时还会返回域的权威响应。 recursion标志是否设置无关紧要。
得到的答案：HEADER：头标志： 回应 ， 授权。 回答 ， recursion有效。