DNS resolution got extremly slow after issuing ipconfig commands I wanted to inspect DHCP messages. To produce them I issued these 2 commands:

sudo ipconfig set en0 BOOTP
sudo ipconfig set en0 DHCP


After that, I am having severe DNS resolution difficulties. It takes up to a minute and several refreshs to even resolve google. What could be the reason for this behaviour?

Output from ifconfig en0:

en0: flags=8963&lt;UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST&gt; mtu 1500
    ether "IPv6 goes here" 
    inet6 "IPv6 goes here"%en0 prefixlen 64 scopeid 0x4 
    inet6 "IPv6 goes here" prefixlen 64 autoconf 
    inet6 "another IPv6 goes here" prefixlen 64 autoconf temporary 
    inet 192.168.1.5 netmask 0xffffff00 broadcast 192.168.1.255
    nd6 options=1&lt;PERFORMNUD&gt;
    media: autoselect
    status: active


EDIT: nslookup does not work
Could your DNS server be very slow and you are clearing the local cache of results and then seeing the delay of the actual resolution / forward / lookup after running the ipconfig

You can time DNS crudely from the command line before and after the script commands:

time host www.google.com &gt;&amp; /dev/null