NETWORK SECURITY
INTRODUCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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68
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21
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53
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56
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Detailed explanation-1: -The answer is DNS is mostly UDP Port 53, but as time progresses, DNS will rely on TCP Port 53 more heavily.
Detailed explanation-2: -The DNS uses TCP Port 53 for zone transfers, for maintaining coherence between the DNS database and the server. The UDP protocol is used when a client sends a query to the DNS server. The TCP protocol should not be used for queries as it gives a lot of information, which is useful to attackers.
Detailed explanation-3: -A DNS client uses a random port above 1023 for both UDP and TCP. You can thus differentiate between the following: A client-to-server query-source port is above 1023, destination port is 53. A server-to-client response-source port is 53, destination port is above 1023.