DNS Paranoia

Using "reflect.dnsp.co"

The “reflect.dnsp.co” test will give you one of two results.

If you query the @dnsp.co resolver itself, it will return your external IP address. If the response returns an IP address other than your own it is indicates that the DNS query was transparently cached or relayed by some other network device.

If you query any other nameserver for "reflect.dnsp.co", the response will return the IP address that that nameserver used to talk to ours.

There may be a difference between your computer’s IP address and your external IP address. This is common and not a cause for concern. It is caused by a technology called "NAT" (network address translation).

Additionally, there may be a difference between the IP address of the nameserver you are querying and the IP address that is returned by the “reflect.dnsp.co” query. For instance, if you are querying Google’s “8.8.8.8” nameserver you will never see “8.8.8.8” as the response. This occurs because the “8.8.8.8” address is really an alias in front of a great many nameservers rather than the address of the nameserver itself.>

Example using your default nameserver:


prompt> dig reflect.dnsp.co
; <<>> DiG 9.8.3-P1 <<>> reflect.dnsp.co
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17115
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;reflect.dnsp.co.        IN    A

;; ANSWER SECTION:
reflect.dnsp.co.    0    IN    A    74.125.19.213 ← IP of your nameserver

;; Query time: 47 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Sun Dec 21 19:38:16 2014
;; MSG SIZE  rcvd: 49

Example querying @dnsp.co directly:


prompt> dig @dnsp.co reflect.dnsp.co
; <<>> DiG 9.8.3-P1 <<>> reflect.dnsp.co @dnsp.co
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36957
;; flags: qr aa ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;reflect.dnsp.co.        IN    A

;; ANSWER SECTION:
reflect.dnsp.co.    0    IN    A    98.211.255.255 ← should be your IP

;; Query time: 34 msec
;; SERVER: 192.155.94.246#53(192.155.94.246)
;; WHEN: Sun Dec 21 19:38:17 2014
;; MSG SIZE  rcvd: 49