getCanonicalHostName is very slow

Question

InetAddress.getByName(ipAddress).getLocalHost().getCanonicalHostName();

The above line takes around 10seconds to execute.

I added the IP and hostname in etc\hosts file and still there is no change.

How does getCanonicalHostName work? Can I get the implementation of that method?

How do I increase the efficiency of this line of code?

Answer 1

In my case the problem was caused by the Npcap driver, which I use for Wireshark. Disabling Npcap Loopback Adapter in Windows Control Panel\Network and Internet\Network Connections fixed the 9 seconds delay that I had.

The delay itself happens in the Inet6AddressImpl.getHostByAddr(byte[] addr) method (called by InetAddress.getCanonicalHostName()), which is native, so it's hard to say what's going on other than it's DNS related.