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Greatestswordsman
Asked: 2012-02-24 21:11:59 +0800 CST

Check remaining TTL for nameserver

  • 772

Is it possible to check how much time is left before a nameserver like 8.8.8.8 will update its records from my nameserver?

domain-name-system bind domain nameserver

2 Answers

  1. Best Answer

    Using dig you can check the TTL of a record - like so:

    ; <<>> DiG 9.7.3 <<>> @8.8.8.8 www.serverfault.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3937
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.serverfault.com.       IN  A

;; ANSWER SECTION:
www.serverfault.com.    1800    IN  CNAME   serverfault.com.
serverfault.com.    1800    IN  A   64.34.119.12

;; Query time: 88 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Thu Feb 23 23:15:23 2012
;; MSG SIZE  rcvd: 67

    Specifically, you'll want to pay attention to the values in the answer (1800 in this case)

    ;; ANSWER SECTION:
www.serverfault.com.    1800    IN  CNAME   serverfault.com.
serverfault.com.    1800    IN  A   64.34.119.12

    1800 is the number of seconds until the TTL expires and the record is refreshed on the nameserver (8.8.8.8).

    If you run the command a few times, you'll see the TTL number go down, so as of the time of writing this, the TTL is now like so (1659 sec)

    ;; ANSWER SECTION:
www.serverfault.com.    1659    IN  CNAME   serverfault.com.
serverfault.com.    1659    IN  A   64.34.119.12
    • 11

  2. For Windows (natively) you can use nslookup.

    C:\>nslookup -debug www.serverfault.com 8.8.8.8

    Got answer:
     HEADER:
         opcode = QUERY, id = 4, rcode = NOERROR
         header flags:  response, want recursion, recursion avail.
         questions = 1,  answers = 2,  authority records = 0,  additional = 0
    QUESTIONS:
        www.serverfault.com, type = A, class = IN
    ANSWERS:
    ->  www.serverfault.com
        canonical name = serverfault.com
        ttl = 1791 (29 mins 51 secs)**
    ->  serverfault.com
        internet address = 64.34.119.12
        ttl = 1791 (29 mins 51 secs)**
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