dnscloudflarecnamea-records

Does a CNAME "hide" the domain you're CNAME'ing to?


Say domain A.COM has a CNAME for www which points to B.COM, and B.COM also has a www CNAME which points to C.COM, and C.COM has multiple A records/IP's.

Is there any way for someone snooping around to query A.COM and see that it's simply pointing to B.COM? Or is it impossible to get that information without having full access to the DNS zone manager (meaning all they would see are the final IP's that C.COM resolve to)?

EDIT: I'm using CloudFlare (A, B, & C), so I'm not sure if that changes the answer. It seems to me they all point to CloudFlare as A records and you can't pull out a CNAME?


Solution

  • No, a CNAME does not hide anything. You can run a dig WWW.A.COM and it will show you the CNAME pointer. That said, casual users browsing your website will never see or know that your website points to C.COM.

    Example:

    $ dig ak.nextag.com
    
    ; <<>> DiG 9.8.3-P1 <<>> ak.nextag.com
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9813
    ;; flags: qr rd ra; QUERY: 1, ANSWER: 11, AUTHORITY: 0, ADDITIONAL: 0
    
    ;; QUESTION SECTION:
    ;ak.nextag.com.         IN  A
    
    ;; ANSWER SECTION:
    ak.nextag.com.      879 IN  CNAME   img.nextag.com.
    img.nextag.com.     86379   IN  CNAME   img05.static-nextag.com.
    img05.static-nextag.com. 7179   IN  CNAME   d2lhs8hfggtuez.cloudfront.net.
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.195
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.200
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.186
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.218
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.251
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.132
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.42
    d2lhs8hfggtuez.cloudfront.net. 39 IN    A   54.230.143.7
    
    ;; Query time: 106 msec
    ;; SERVER: 10.100.51.31#53(10.100.51.31)
    ;; WHEN: Sat Jul  8 01:18:44 2017
    ;; MSG SIZE  rcvd: 254