Can someone please help me understand this problem? The book doesn't explain this very well so seeking outside help. Why are the TCP values those, Why is the there nothing for the first 2 source ports, and how is the TTL determined? I know the TTL starts with 100 but why is there an x/y? Is it because of some unknown variable we don't know about? If that is so why is there a need to get an x and a y? Also why is the Net3 in TTL 200 + x + y?

NET 3 NET 1 Nat 1 NET 2 Assume the following addresses Nat 1 Nat 1 192.168.5.254 (for the NET 1) 129.186.4.1 (for the NET 2) H1 192.168.5.5 H3 129.186.2.8 Router 3 129.186.4.253 (for NET 2) Router 1 129.186.4.254 (for the NET 2) Router 3 129.186.2.254 (the NET 3) Router 1 10.0.0.5 (for the internet side) Assume the NAT is a dynamic NAT and that 192.168.5.0/24 is the internal network. Assume the following request packet is delivered to the IP layer from the TCP layer on host H1 with an intended destination of H3. (Assume the other TCP header values are correct) TCP source port 9333 TCP destination port 80 500 bytes of data Assume all ARP and DNS tables are current. For each of the points in the network listed below show the values for the following fields in the packets (Assume the initial value of the time to live field is 100 when the packet is sent by either host H1 or H3) (If the value for a field is not specified you can assume a alue) Show the fields in the reply packet at each of the points in the network. Net 1 (request) Net2 Net3 Net 1(reply) Net 2 Net 3 TCP 192.168.5 129.186.4.2 192.168.4.1 129.186.4.25 129.186.4.25 129.186.2.25 Layer: 254 53 4 Source port 9333 80 80 80 Dest port 80 80 80 9333 9333 9333 IP Layer 100 100+x 100 y 100- 200+x 100+x 200+x+y SRC IP10.0.0.5 10.0.0.5 10.0.0.5 192.168.5.25 129.186.4.25 129.186.2.25 Dest IP 192.168.5 129.186.4.2 129.186.2 25 10.0.0.5 10.0.0.5 10.0.0.5 254 54