Term 121
Designated Router
A router elected in an OSPF multi-access network to manage link-state updates and reduce routing protocol traffic.
Acronym study
Terms 121–150 of 610 SY0-701 acronyms and key terms. Each entry includes a plain-English definition and a link to the full 800-word glossary page with exam context and practice questions.
Term 121
A router elected in an OSPF multi-access network to manage link-state updates and reduce routing protocol traffic.
Term 122
Device compliance is the process of ensuring that a device meets an organization's security and configuration policies before it can access network resources.
Term 123
Device risk is the chance that a computer, phone, or other endpoint could cause a security problem or data leak because it is not properly managed or protected.
Term 124
Dynamic Host Configuration Protocol (DHCP) automatically assigns IP addresses and network settings to devices on a network, so they can communicate without manual configuration.
Term 125
A DHCP pool is a reserved set of IP addresses that a DHCP server can assign to devices on a network automatically when they request a connection.
Term 126
A network device or feature that forwards DHCP broadcast messages between clients and servers on different subnets so that IP address assignment works across multiple network segments without a separate DHCP server on each one.
Term 127
A DHCP server is a network device or service that automatically assigns IP addresses and other network configuration parameters to devices on a network, eliminating the need for manual configuration.
Term 128
DHCP snooping is a network security feature that filters untrusted DHCP messages to prevent rogue DHCP servers from giving out false IP addresses.
Term 129
A dictionary attack is a cyberattack method where an attacker tries to break into a system by rapidly testing thousands of common passwords or passphrases from a precompiled list.
Term 130
Diffie-Hellman is a cryptographic protocol that allows two parties to securely exchange a shared secret key over an untrusted network like the internet.
Term 131
A digital certificate is an electronic document that verifies the identity of a person, device, or website and enables secure encrypted communication over the internet.
Term 132
A cryptographic technique used to verify the authenticity and integrity of a digital message or document, ensuring it came from the claimed sender and was not altered.
Term 133
Disaster recovery is a set of policies, procedures, and tools that help an organization restore critical IT systems and data after a disruptive event.
Term 134
Disk encryption is the process of converting data on a storage device into a coded form that can only be read with the correct decryption key, protecting it from unauthorized access.
Term 135
A cyberattack where many compromised computers flood a target system with traffic, making it unavailable to legitimate users.
Term 136
Data Loss Prevention — security technology that detects and prevents unauthorised transmission of sensitive data outside an organisation.
Term 137
A DLP policy is a set of rules that an organization uses to prevent sensitive data from being lost, stolen, or accidentally exposed, whether it is in use, in motion, or at rest.
Term 138
A DMZ (demilitarized zone) is a network segment that sits between an internal private network and the public internet, hosting publicly accessible services while keeping the internal network isolated.
Term 139
DNS is the system that translates human-friendly domain names like example.com into machine-readable IP addresses so computers can find each other on a network.
Term 140
A DNS log is a record of all Domain Name System queries and responses that pass through a server, providing a trail of which domains were requested, by whom, and when.
Term 141
DNS over HTTPS is a protocol that sends Domain Name System queries and responses over the encrypted HTTPS protocol to protect user privacy and prevent tampering.
Term 142
DNS over TLS encrypts DNS queries using the Transport Layer Security protocol to prevent eavesdropping and tampering.
Term 143
DNS poisoning is a cyberattack that corrupts a DNS resolver's cache with false information, redirecting users to malicious websites without their knowledge.
Term 144
A DNS record is a set of instructions stored on a DNS server that tells clients how to interact with a domain, most commonly by mapping a human-readable domain name to an IP address.
Term 145
A DNS zone is a distinct part of the global Domain Name System (DNS) namespace that is delegated to a specific administrator or organization for management, containing resource records for a domain.
Term 146
DNSSEC adds cryptographic signatures to DNS records to ensure data authenticity and integrity, preventing cache poisoning and spoofing attacks.
Term 147
DoH encrypts DNS queries within HTTPS traffic to prevent eavesdropping and manipulation of domain name resolution.
Term 148
A set of protocols that add digital signatures to DNS data to verify its authenticity and integrity.
Term 149
DMARC is an email authentication protocol that helps prevent spoofing and phishing by verifying that incoming email really comes from the domain it claims to be from and tells receiving servers what to do if verification fails.
Term 150
DomainKeys Identified Mail is an email authentication method that allows a domain to cryptographically sign its outgoing messages so receiving servers can verify the sender's domain is legitimate and the message was not tampered with.