System Administration related to Security (The history of resolution…
System Administration related to Security
Two Most Important Network Services
DHCP : Dynamic Host Configuration Protocol
, ranges of IP addresses, which was better than
Uses pool to pick IP addresses
Uses "lease" system
was an extension of BootP so that relay agents would be able to relay either
or the new
DORA - Discover, Offer, Request and Acknowledge
gives client : IP, Subnet Mask, Default Gateway IP, DHCP Server Address and DNS Server Address
Clients send DHCP discover messages as broadcasts, and relay agents turn them into unicasts.
Clients learn what their DNS servers are from their DHCP server.
DNS : Domain Name System
FQDN : Fully Qualified Domain Name
Client's DNS server will not know the answer and escalates the query to one of the 13 root DNS servers. There are actually hundreds of machines in many countries around the world acting together sharing 13 logical IP addresses.
Root server will respond back to the client's DNS server with a referral. Every top level domain - .com, .net, .edu is maintained by a registry.
Client asks DNS server for the answer
DNS server contacts 13 worldwide root DNS servers
root DNS responds to client's DNS server with TLD of that website
Client's DNS server contacts TLD and requests the IP for that website
TLD responds with answer
The history of resolution protocols
ARP : Address Resolution Procol
- First in use. Matches an IP address to corresponding Mac address. Does not deal with assigning IP addresses to devices
RARP : Reverse Address Resolution Protocol
: Upgraded version of ARP. Matches a Mac address to a corresponding IP address
BootP : Bootstrap particle
- Last update for ARP and RARP. A machine would boot up, send a request to the BootP server with its Mac address, and it would be assigned an IP address that the admin chose for that Mac address. The invention of DHCP revolutionized this system.