今天客服美眉問我如果用戶端nslookup一個域名的時候提示如下錯誤,有什麼原因可以造成:
先看一下愛正确的解析過程:
我當初說如果這個域名本地的DNS解析不出來就是提示域名不存在,而如果解析除了這個域名cname給咱們,但是這個cname解析不出來,應該提示解析失敗,後來感覺不妥,就自己找了個域名試試,果然我了解錯了,如果這個域名cname的域名也解析不出來,也提示域名不存在
比如我把te4.sportsvc.cn CNAME到www.fanfeildld.com,而這個www.fanfeildld.com是解析不出來的,
先看一下dig圖:
看出解析出cname,因為解析不到cname,是以提示nxdomain
然後再看nslookup圖:
看到也是提示域名不存在
結果就是這樣,我們可以開啟nslookup的set d2模式,看具體的解析過程,也可以看到解析出cname後,就沒有解析了
> set d2
> te3.sportsvc.cn.
伺服器: cc-core.chinacache.local
Address: 192.168.1.199
------------
SendRequest(), len 33
HEADER:
opcode = QUERY, id = 10, rcode = NOERROR
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional = 0
QUESTIONS:
te3.sportsvc.cn, type = A, class = IN
Got answer (140 bytes):
opcode = QUERY, id = 10, rcode = NXDOMAIN
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 1, additional = 0
ANSWERS:
-> te3.sportsvc.cn
type = CNAME, class = IN, dlen = 22
canonical name = www.fantefeildld.com
ttl = 3515 (58 mins 35 secs)
AUTHORITY RECORDS:
-> com
type = SOA, class = IN, dlen = 61
ttl = 815 (13 mins 35 secs)
primary name server = a.gtld-servers.net
responsible mail addr = nstld.verisign-grs.com
serial = 1389254445
refresh = 1800 (30 mins)
retry = 900 (15 mins)
expire = 604800 (7 days)
default TTL = 86400 (1 day)