 Now, let us see what are the issues, common issues that occur in transport and application layers. One of the important things is firewall settings. I am now looking at the web server which hosts hotel.com websites and we can and if you can see there is an option to configure firewall options. You can configure firewall for each of the interfaces that has been connected to the device and you can either allow or deny some specific types of packets that is you can either allow or block IP packets, ping packets, TCP, UDP etc. from either one IP address or a set of IP addresses or you can also allow or block some specific ports. Here I have already added one rule which says that you can allow TCP packets coming from this IP address from any port to any port in this device. You can use these options in order to configure your servers so that any unwanted requests do not come to your server or if you want to block some type of requests going out of your network. Another important concept is your services where you have actually set up DHCP, DNS or web services etc. Let us look into more detail. Now this is again the server which hosts the website hotel.com. There are couple of checks you need to do. One is you have to ensure that the HTTP service is actually turned on in your web service and then you have to ensure that the web pages are present in their places. This is with respect to the web server which is hosting. If we take a look at the DNS which has the DNS records for all the websites in this network, again we should ensure that the DNS service is on and the DNS records are right. For example, the mapping between the logical address and IP address should be correct. If by mistake you have entered incorrect IP address here then it would lead to an error. So things like these should be taken care of.