dns1.plala.or.jp.　210.153.0.129
dns2.plala.or.jp.　210.153.0.130
ns2.sphere.ad.jp.　202.239.113.18
いずれも返ってくるようです。

; <<>> DiG 8.3 <<>> @dns1.plala.or.jp school4.2ch.net
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUERY SECTION:
;; school4.2ch.net, type = A, class = IN

;; ANSWER SECTION:
school4.2ch.net. 1m29s IN A 206.223.149.235

;; AUTHORITY SECTION:
2ch.net. 4m46s IN NS ns1.maido3.com.
2ch.net. 4m46s IN NS ns2.maido3.com.

;; ADDITIONAL SECTION:
ns1.maido3.com. 1d3h53m19s IN A 206.223.148.254
ns2.maido3.com. 1d3h53m19s IN A 206.223.147.254

いわゆる「DNSキャッシュのクリア」を実施してみるとよいカモです。
http://homepage2.nifty.com/winfaq/wxp/network.html#1212