DNS解析追踪

dig跟踪dns解析过程

dig可以跟踪dns的解析过程，+trace 表示开启跟踪查询，+nodnssec 表示禁止 DNS 安全扩展：

$ dig +trace +nodnssec time.geekbang.org

; <<>> DiG 9.11.3-1ubuntu1.3-Ubuntu <<>> +trace +nodnssec time.geekbang.org
;; global options: +cmd
.            322086    IN    NS    m.root-servers.net.
.            322086    IN    NS    a.root-servers.net.
.            322086    IN    NS    i.root-servers.net.
.            322086    IN    NS    d.root-servers.net.
.            322086    IN    NS    g.root-servers.net.
.            322086    IN    NS    l.root-servers.net.
.            322086    IN    NS    c.root-servers.net.
.            322086    IN    NS    b.root-servers.net.
.            322086    IN    NS    h.root-servers.net.
.            322086    IN    NS    e.root-servers.net.
.            322086    IN    NS    k.root-servers.net.
.            322086    IN    NS    j.root-servers.net.
.            322086    IN    NS    f.root-servers.net.
;; Received 239 bytes from 114.114.114.114#53(114.114.114.114) in 1340 ms

org.            172800    IN    NS    a0.org.afilias-nst.info.
org.            172800    IN    NS    a2.org.afilias-nst.info.
org.            172800    IN    NS    b0.org.afilias-nst.org.
org.            172800    IN    NS    b2.org.afilias-nst.org.
org.            172800    IN    NS    c0.org.afilias-nst.info.
org.            172800    IN    NS    d0.org.afilias-nst.org.
;; Received 448 bytes from 198.97.190.53#53(h.root-servers.net) in 708 ms

geekbang.org.        86400    IN    NS    dns9.hichina.com.
geekbang.org.        86400    IN    NS    dns10.hichina.com.
;; Received 96 bytes from 199.19.54.1#53(b0.org.afilias-nst.org) in 1833 ms

time.geekbang.org.    600    IN    A    39.106.233.176
;; Received 62 bytes from 140.205.41.16#53(dns10.hichina.com) in 4 ms