Ho!
So able to reproduce this. But its depending what machine you are using, what reply you get. On some if get random results, on others i get nxdomain, on this exact same server.
I can reproduce the above. I suggest dropping 202.106.182.243 too.
< f.surbl.org. 86400 IN A 202.106.182.243 113d111 < k.surbl.org. 86400 IN A 123.125.50.246 124d121 < l.surbl.org. 86400 IN A 202.106.182.244
Those 3, all running a older vers rbldnsd, we will follow up with the people kindly hosting those nameservers for us.
Bye, Raymond.