Refer to the exhibit. Which statement is true about the configuration?（）

• A、Hosts belonging to DHCP pool  1 and pool 2 will retain their IP settings for 30 hours before they must renew.
• B、Hosts will receive IP settings from pool 1 until the addresses run out, and then hosts will receive the settings from pool 2.
• C、Hosts in the 10.10.20.0/24 subnet will u se 10.10.20.50 as its DNS server.
• D、DHCP pool 0 needs to have the ip dhcp excluded - address command to exclude the default router and DNS servers.