Hi Visvanath,
let me add a note about "my" vs "your" caching .
My last post describes content/resource caching whilst in your last post you're talking about DNS caching which cannot be controlled via HTTP Headers, being something depending on some local settings of your web browser.
Open a new tab in Firefox and write about:config, search for dnsCache, then you'll find three items:
- network.dnsCacheEntries
- network.dnsCacheExpiration
- network.dnsCacheExpirationGracePeriod
those values will rule the local DNS cache of your Firefox application (in my 59.0.2 64bit running on Win 10 the values are 400/60/60 respectively).
Even the OS has its own DNS client cache, if you have tried to resolve the name using ping <hostname> from a terminal: for example in Windows you can flush it via ipconfig /flushdns, https://support.apple.com/en-us/HT202516 for OSX and in Linux it depends on the distro and user tuning e.g. by means of dnsmaq.
HTH,
Matteo