A question that CCIE will not? ccie lab v5 topology

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topic

The network configuration of the two servers A and B is as follows. The subnet mask of the B server should be 24 bits. Now it is accidentally configured as 27 bits. Can they still communicate normally?

        A server:

        IP&PREFIX: 192.168.26.129/255.255.255.0

        GW: 192.168.26.2

        B server:

        IP&PREFIX: 192.168.26.3/255.255.255.224

        GW: 192.168.26.2

analysis

A--->B

Let's first use the A server to ping the B server. Can it pass? We are going to analyze the process positively:

    A will use its own subnet mask and B's IP address to do the AND operation, so as to determine whether the destination IP address is in the same network segment as its current IP address. After A's judgment, it is found that the destination IP is indeed a network. Paragraph.

    Send an ARP broadcast. A will send an ARP broadcast to access the MAC address of the B server, and B has to respond, so A gets the MAC address of B.

    B will also judge whether A is on a network segment with himself, and finds that A and himself are not in a network segment. After B's judgment, the network segment where A is located is 192.168.26.128.0/255.255.255.224.0, and B himself The network segment is 192.168.26.0/255.255.224.0, and the packet is given to the gateway.

    A---ping---->B results in the request packet can reach the B server, and the response packet of B cannot reach the A server. The result is that the A server requests timeout in the pingB server (in the absence of a gateway).

B--->A

The communication between the B server and the A server is very good. B judges that A and itself are not in a network segment, and directly delivers the packet to the gateway. If there is no gateway, the request packet of B cannot reach the A server at all, so B and The result of A communication is that the data packet cannot arrive!