You may occasionally get into a situation where the DNS on your Mac needs to be flushed from the system in order for a new server or some other DNS address change.
A DNS cache contains entries that translate Internet domain names *such as “compnetworking.about.com”) to IP addresses. The Internet’s Domain Name System (DNS) involves caching on both Internet DNS servers and on the client computers that contact DNS servers. These caches provide an efficient way for DNS to efficiently keep the Internet synchronized as the IP addresses of some servers change and as new servers come online.
OS X Yosemite have “new systems” to manage DNS which is
- MDNS Cache (Multicast DNS)
- UDNS Cache (Unicast DNS)
This post show how we clear the cache. Open the terminal and run this command
Clear MDNS Cache
sudo discoveryutil mdnsflushcache
Hit return and enter the admin password when requested.
Clear UDNS Cache
sudo discoveryutil udnsflushcaches
Again, hit return and enter the admin password when requested.
Flush and Reset All DNS Caches
sudo discoveryutil mdnsflushcache;sudo discoveryutil udnsflushcaches;say flushed
If your Mac is on 10.10.4, you need to use this command
sudo dscacheutil -flushcache;sudo killall -HUP mDNSResponder;say cache flushed