Hey!
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Answers:
1. refused - B). packet was not sent in the proper format.
2. network unreachable - A). computer was unable to connect to DNS server.
3. format error - C). packet was not sent in the proper format.
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Step-by-step explanation:
1. refused - this server is not accepting emails from that I.P. address.
2. network unreachable - network is unstable or not on.
3. format error - a problem due to missing system files.
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Hope This Helped! Good Luck!