What effect does the following command have on TCP packets? iptables- A INPUT d 10.142.232.1 p tcp --dport 20:21 j ACCEPT

Question

Options

• AForward all TCP traffic not on port 20 or 21 to the IP address 10.142.232.1
• BDrop all TCP traffic coming from 10.142.232.1 destined for port 20 or 21.
• CAccept only TCP traffic from 10.142.232.1 destined for port 20 or 21.
• DAccept all TCP traffic on port 20 and 21 for the IP address 10.142.232.1

• A
  3% (1)
• B
  9% (3)
• C
  3% (1)
• D
  85% (28)

Explanation

Option D is correct because the -d 10.142.232.1 flag specifies the destination IP address, -p tcp --dport 20:21 matches TCP traffic on ports 20 and 21 (FTP data and control), and -j ACCEPT tells iptables to allow the matching packets through the INPUT chain.

Why the distractors are wrong:

• A is wrong on two counts: the action is ACCEPT (not forward/redirect), and the rule targets ports 20-21 specifically, not traffic outside those ports.
• B confuses -d (destination) with -s (source), and misreads -j ACCEPT as a drop action - the rule accepts, not drops.
• C also confuses -d with -s; the IP is the traffic's destination, not its source/origin.

Memory tip: In iptables, think "d = destination, s = source" - -d means "going to this IP," and -s means "coming from this IP." If you can keep those two straight, you can immediately eliminate any answer that reverses the direction.

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