Credit: Post based on CISSP course presented by Dennis Lee, November 2018
Layer 5 protocols coordinate the orderly exchange of information. They include:
The Remote Procedure Call (RPC) Protocol which is utilized in client-server environments and Secure RPC which uses mutual authentication for client & server to authenticate one another.
Layer 6 protocols are responsible for giving applications access to the network services, i.e. they help applications talk to the network. An example is Microsoft Outlook using Layer 6 protocols such as SMTP, POP3, or IMAP to handle email transmission on the network. Other examples include:
The Domain Name System (DNS) protocol which is a translation service to resolve Fully Qualified Domain Names (FQDN) to IP addresses. The way this works is:
- Browser sends domain to ISP for lookup
- ISP DNS goes through recursive search, first to Root DNS, which will return local .ORG DNS address
- .ORG DNS will return IP address of DNS server of actual website Website
- DNS server will return IP address of actual website to ISP DNS
- ISP DNS then returns actual website IP address to Browser
DNS Security (DNS-SEC) is a protocol designed to combat DNS cache poisoning using digital signatures to verify that DNS data is coming from authentic sources.
Network Address Translation (NAT) is the translation between public internet IP addresses and local (private) IP addresses. Private IP ranges include:
- 10.0.0.0 – 10.255.255.255
- 172.16.0.0 – 172.31.255.255
- 192.168.0.0 – 192.168.255.255
Excellent Tips 