The server seems to be up to me. Your sites being unreachable could be anything--not necessarily an entire server being down.
What is the domain name that you can't reach?
Pinging apu.dreamhost.com [220.127.116.11] with 32 bytes of data:
Reply from 18.104.22.168: bytes=32 time=65ms TTL=46
Reply from 22.214.171.124: bytes=32 time=79ms TTL=46
Reply from 126.96.36.199: bytes=32 time=64ms TTL=46
Reply from 188.8.131.52: bytes=32 time=67ms TTL=46
Ping statistics for 184.108.40.206:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 64ms, Maximum = 79ms, Average = 68ms
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