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Application protocol used for mail storage and retrieval on a server. IMAP is used on 143/tcp and 993/tcp for TLS-level security. IMAP supports permanent connections to a server, multiple client connections to the same mailbox, folder organization, and the cre...

Application protocol used to send mail between hosts on the internet. SMTP uses 25/tcp for messages between mail servers. The sender's SMTP server discovers the recipient's SMTP server using the domain name part of the recipient's email address (i.e. the lilt...

The programming and query language for relational databases.

A dedicated hardware device that provides general storage for an entire network. Usually made with a Linux-based OS that's access via a webpage using an IP address or a domain. NASs are made to fill a file-server role. They (should) have automatic backup capab...

Application protocol that manages VoIP and conferencing communications. SIP is responsible for managing user discovery, availability advertising, negotiating session parameters, session management and session termination. SIP endpoints are the end user device...

Network protocol responsible for delivering audio and video data over IP-based networks. RTP doesn't have a fixed port, but operates on the range 16384-32767/udp. RTP implements some of the reliability features usually associated with TCP communications. RTP...

Network protocol responsible for the monitoring and feedback of realtime data communications used in RTP.

A hardware appliance or software program that distributes incoming client requests across a set of configured servers, providing fault tolerance and improving throughput. Layer 4 Switch A basic load balancer that makes forwarding decisions on IP address and ...

Cisco proprietary protocol designed to provide both redundancy and load balancing for IP traffic.

aliases: FHRP Networking technique that configures failover routers that serve as the default gateway in a subnet. There are several FHRPs: Virtual Router Redundancy Protocol Hot Standby Router Protocol Gateway Load Balancing Protocol

aliases: VRRP Open-source standard protocol for configuring failover routers. VRRP is highly similar to HSRP, with the main differences being terminology and packet formats. In VRRP, the active router is called the 'master,' and the standby routers ...

aliases: HSRP Proprietary protocol developed by Cisco. Allows multiple physical routers to serve as a single default gateway for a subnet. Each router part of the mesh needs an interface connected with the subnet, a unique MAC address and a unique IP addre...

The public address of a load balanced cluster that is shared among the nodes. Also called a floating address.

A widely used software tool used for IP scanning. Nmap requires at least the IP address or the subnet to scan. When used without any switches or flags (e.g. nmap 10.0.0.116), Nmap sends a TCP ACK packet to ports 80 and 443 of the target IP to determine if a ho...

An enumeration of some common host discovery protocols. Cisco Discovery Protocol Used in all Cisco devices. Link Layer Discovery Protocol IEEE maintained protocol similar to CDP. Neighbor Discovery IPv6 host discovery protocol.

A proprietary host discovery protocol used in all Cisco network appliances. CDP uses Data Link layer multicast messaging to second status announcements over local interfaces every minute. It uses the multicast v6 address 01:00:0c:cc:cc:cc. Each device keeps a ...

A command that sanitizes storage drives. SE has been a part of the SATA and SAS specifications since 2011. For HDDs SE performs a single zero-fill pass. For SSDs Marks all blocks as empty. Instead of wiping each block directly, SE relies on the drives automati...

An enumeration of the eight logging levels commonly used in computers. Name Description Level Emergency System is unusable (kernel panic) 0 Alert Condition requiring immediate correction. 1 Critical A fault that will require immediate correction is ...