我的一个名称服务器出了问题。当我使用不带 +trace 的 nslookup 或 dig 时，一切都正常。但当我使用带 +trace 的 nslookup 或 dig 时，就会出现错误
连接超时错误；无法访问服务器。
这导致我的域名服务器无法从主服务器更新其记录。以下是我的检查：
1.============Iptables Stop==========
[root@dns2 ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
2. ============Dig without +trace working==========
root@dns2 ~]# dig www.google.com +notrace
; <<>> DiG 9.7.0-P2-RedHat-9.7.0-17.P2.el5_9.1 <<>> www.google.com +notrace
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17007
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 0
;; QUESTION SECTION:
;www.google.com. IN A
;; ANSWER SECTION:
www.google.com. 74 IN A 216.58.199.4
;; AUTHORITY SECTION:
google.com. 172572 IN NS ns2.google.com.
google.com. 172572 IN NS ns1.google.com.
google.com. 172572 IN NS ns4.google.com.
google.com. 172572 IN NS ns3.google.com.
;; Query time: 2 msec
;; SERVER: 124.108.4.131#53(124.108.4.131)
;; WHEN: Mon Aug 26 16:08:51 2019
;; MSG SIZE rcvd: 120
[root@dns2 ~]#
3.=============dig with +trace error=====
[root@dns2 ~]# dig www.google.com +trace
; <<>> DiG 9.7.0-P2-RedHat-9.7.0-17.P2.el5_9.1 <<>> www.google.com +trace
;; global options: +cmd
. 518076 IN NS g.root-servers.net.
. 518076 IN NS c.root-servers.net.
. 518076 IN NS i.root-servers.net.
. 518076 IN NS b.root-servers.net.
. 518076 IN NS d.root-servers.net.
. 518076 IN NS a.root-servers.net.
. 518076 IN NS f.root-servers.net.
. 518076 IN NS l.root-servers.net.
. 518076 IN NS e.root-servers.net.
. 518076 IN NS m.root-servers.net.
. 518076 IN NS h.root-servers.net.
. 518076 IN NS k.root-servers.net.
. 518076 IN NS j.root-servers.net.
;; Received 508 bytes from 127.0.0.1#53(127.0.0.1) in 1 ms
;; connection timed out; no servers could be reached
===========================
您的答复很满意。