Nope, this is not an ISP. Turk Telekom is stated-owned broadband internet (infrastructure) company. All of the ISPs are having the same peering. I checked your link through TTNet. We also have Superonline and Smile as main ISPs.
Details courtesy of Wikipedia: Privatized in 2005. "55% of the shares of Turk Telekom belongs to Oger Telekomünikasyon A.Ş. and 30% of the shares belongs to Undersecretariat of Treasure of Turkey. The remaining 15% of shares has been offered to the public." Oger Telekom is apparently 100% privately owned by the Hariri family.
So, still 30% state owned. As one point of reference, the German government still holds 15% directly plus 17% indirectly of Deutsche Telekom. France and Orange (nee France Telecom) are similar.
Would you mind posting a traceroute to 8.8.8.8? I'm curious as to the "how", e.g. if they're announcing the IP/subnet into BGP or (assuming traffic flows through them) if they're just transparently redirecting (DNAT, in effect) it to their own DNS servers.
traceroute to 208.67.222.222 (208.67.222.222), 30 hops max, 60 byte packets
1 192.168.1.1 (192.168.1.1) 2.525 ms 3.372 ms 8.410 ms
2 78.180.240.1.dynamic.ttnet.com.tr (78.180.240.1) 26.861 ms 28.677 ms 30.683 ms
3 81.212.78.13.static.turktelekom.com.tr (81.212.78.13) 32.834 ms 33.887 ms 34.726 ms
4 gayrettepe-t2-3-gayrettepe-t3-5.turktelekom.com.tr.205.212.81.in-addr.arpa (81.212.205.105) 36.738 ms 37.718 ms 39.747 ms
5 ulus-t2-3-gayrettepe-t2-3.turktelekom.com.tr.204.212.81.in-addr.arpa (81.212.204.205) 48.947 ms 49.867 ms 51.937 ms
6 ulus-t3-4-ulus-t2-3.turktelekom.com.tr.204.212.81.in-addr.arpa (81.212.204.149) 56.001 ms 27.122 ms 29.496 ms
7 * * *
...
30 * * *
8.8.8.8 gives similar (indeed identical if I've good eye-diff skills) output.
Interestingly enough, it throws an error ("Please enter a valid IPv4/IPv6 address!") when I ask it for the routes it has for 8.8.4.0/24 or 8.8.8.0/24. If I ask for 8.8.33.0/24 (the "closest" subnet I see in my own BGP tables), it responds normally.
Right, I'm sure they are (they pretty much have to, unless they want to make it harder on themselves)... there's no reason they'd need to filter the /24s out, unless they're afraid that maybe Google would start using other IPs in the same /24 to help the Turks bypass it or something.
For the last paragraph, I should add that Yandex was founded before Google. http://en.wikipedia.org/wiki/Yandex It is not an application of a global idea.
