- querying a DNS server gives you a list of every computer name and IP address that it serves
- DNS Security Extensions (DNSSEC) - a set of authentication and authorization specifications designed to prevent impersonations of DNS servers
- implemented through extension mechanism for DNS (EDNS)
- a specifcation that expands several parameter sizes
Troubleshooting DNS
- most DNS problems result from a problem with the client systems
- run ipconfig /flushdns on windows to eliminate any DNS caches on the local system
- ping
- run ping with the name of a well-known website
- if you get a "server not found error" run ping using just the IP address
- if ping works with the IP address but not with the web site name, you have a DNS problem
- once a problem with DNS is discovered, check to make sure the system has the correct DNS server entry
- run ipconfig /all to see if those DNS settings are the same as the ones in the server
- if they aren't, refresh the DHCP settings
- if the correct DNS settings for the DNS server and the DNS settings in ipconfig /all math those settings, the problem is with the DNS server itself
- nslookup (Name Server Lookup) enables DNS server queries
- allows the query of all types of information from a DNS server and change the system uses DNS
- running nslookup outputs an IP address and the name of the default DNS server
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