A record The DNS record that points a domain or hostname to an IP address

CIDR Classless Internet Domain Routing is a way of representing a range of IPs by specifying how many bits within the final octet are used for specific hosts as opposed to addressing the block itself.

DNS records The records kept on the nameservers that tell other machines online how to reach any given function of the domain.

Domain Name An alphanumeric name registered to an owner to point to email, web and other internet related services.

Headers A section of an email detailing the path the email took from sender to recipient, including servers, the time the servers were reached, and any messages they returned when dealing with the email.

Hostname A domain name or part of a domain which points to an IP, www.example.com would be a hostname or host so long as it points to an IP.

IP address The unique numeric identifier or address for any given connection online. Consists of 4 numbers from 0-255 seperated by a ".".

IPv6 A new IP protocol designed to create more addresses than the current IP system.

Mailserver A server responsible for sending and receiving email.

Mechanisms

MX record Short for Mail Exchanger, the MX record is a DNS record specifying which mailserver is responsible for the domain.

Nameservers The machines which direct domain names to the IPs and servers that make them function. There are 2 ways nameservers are used. Authoritative nameservers keep the records for a given domain name which are the final authority on where it resides. Local resolution nameservers are the machines that look for a domain name when you try to access it through your ISP.

PTR record The DNS records which point the IP address to the appropriate hostname.

Servers Machines responsible for a given function of a domain name, such as web hosting or email, are refered to as servers.

Spam Unsolicited bulk commercial email, basically advertisements sent over email to extremely large numbers of people at once. Also used sometimed in reference to other intrusive forms of online advertising, eg. usenet spam or comments spamming on online journals.

Spoofing The practice of falsifying email headers to disguise the origin of an email for the purpose of spamming.

TXT record A multi purpose record which allows someone to assign any text string of less than 255 characters to a host name.