DNS Servers#
A DNS server is a computer running DNS server software. * Protocols: Primarily UDP but sometimes TCP * Port: 53
Root Servers#
- DNS starts with a '.'
- Delegates name resolution to other DNS servers
Top-Level Domain (TLD) Servers#
- These are all the '.com' '.org' '.net' '.edu' '.gov', etc.
- ICANN has the authority to create new TLDs.
Second-Level DNS Servers#
Handle millions of names like totalsem.com, alexkraker.net, etc
Name Servers#
DNS Zone#
- Foward Lookup Zone Where IPs and FQDNs for the devices in a domain are stored.
- Reverse Lookup Zone
- Cached Lookups Previously resolved FQDN's are cached.
Configuration#
- Authoritative Store IP addresses and FQDN's of systems for a particular domain or domains.
- Cache-only Never the authoritative nameserver. Communicate with other DNS servers to resolve domains.
DNS Records#
Location of DNS Servers#
- Local
- Usually private DNS
- Typically forwards DNS for which it's not the authoritative nameserver
- External Any DNS server that is not internal to an organization.
Dynamic DNS#
Works together with DHCP to dynamically update IP addresses of forward lookup zones * IPAM IP Address Management Protocol used to establish DNS when IP addresses change. Used to communicate between DHCP and DNS server.