Domain Name Service
DII Network Engineering maintains DNS services for a majority of the State of Vermont’s domains. DNS systems provide a critical service for people and systems to resolve names like www.google.com to the host IP 220.127.116.11. On the surface most network users will only see this function of DNS, but DNS also provides significantly more information to the computer systems that rely on it.
Within DNS there are many types of records like: Mail Exchange (MX) that identify what mail systems exist within a domain, Sender Policy Framework (SPF) records that tell mail systems what hosts are authorized to send mail for the domain, and Address Record (A) like a web server name www.google.com. Each of these record type have many settings that tell the world where to find systems, how to interact with them, how often to check to see if they have moved, what preference hosts should be attempted to be reached. There are roughly 29 different types of DNS records that inform the world about a domain.
What is the significance of this to me and my agency or department?
- DNS can be thought of as a network phone book. If there are multiple hosts performing the same role for redundancy like e-mail the domain would contain multiple MX entries with preference weight settings to distribute (or not) mail across all the mail hosts.
- If a department is upgrading a web service and the host is moving to a new network address there are DNS settings call Time To Live (TTL) settings that will tell the internet world how often to check back with the authoritative DNS for any changes. Lowering this to ten minutes days prior to the migration will ensure the world sees the changes quickly. Often if this is not done correctly the world will continue to try to go to the old location for a day or more until the TTL expires.
- Often internal (departmental) DNS servers are utilized for internal domain use like AHS.local. This is one approach to keep private host information from being advertised out to the world. DII Network Engineering provides internet facing DNS services for those hosts that need to be reached by the world to the real domain name like ahs.state.vt.us. This is a solid solution to deal with this security issue but does add some complexity to the network.
Any domains in use or planned for the State of Vermont must be communicated to and approved by DII’s Web Director.
To establish or change Domain Name Services a work order must be created in the Footprints Help Desk Support System. If you do not have an account on this system one can be created by contacting the DII helpdesk at 802-828-3544.