(Fuugetu translated 2 comments of Iseki's.)
It seems this issue is bug of mono.
Rather than bug, it seems that mono have no function for picking up time of IP cache.
so I can't help it.
Later, I checked out the source code mono-3.12.1. I could not find the part of IP cache.
It maybe around this part... But I know that the code read gethostbyname() so on finally.
So I made the program what such as following. Then changed A-record by DNS, it was changed immediately.
public class TestClass
public static void Main(string args)
foreach (IPAddress host in Dns.GetHostAddresses("test.jogrid.net"))
I am wondering if mono have cache of IP.
or Is it my misunderstanding something ?