While using Wireshark to troubleshoot a Domain Name System (DNS) issue for a server that sits behind a firewall that performs Network Address Translation (NAT), I noticed a DNS response coming back where Wireshark showed the following in the "Info" field for a packet:
Standard query response 0x21e1 No such name PTR 5.1.168.192.in-addr.arpa SOA prisoner.iana.org
The server for which I was performing the troubleshooting has an IP address of 192.168.1.5, which is a private IP address. There are 3 private IP address ranges; these ranges are also sometimes referred to as "RFC 1918 addresses", since the private IP address space is defined in RFC 1918 . A Request for Comments (RFC) is a document published by the Internet Engineering Task Force (IETF). Some RFCs, such as RFC 1918 become Internet Standards.
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