Remember EDNS
Full name: Extension Mechanisms for DNS
Memory aid: Extend DNS without replacing the whole naming system.
Larger UDP responses can still encounter fragmentation or path issues.
Study area: Protocols & logical ports · Batch 7
Relevant study for: CompTIA Network+ N10-009 · Cisco CCNA 200-301 · CompTIA A+ Core 1 220-1201 · CompTIA Security+ SY0-701 · ISC2 CISSP 2024 outline
Practice with exam flashcards →Networking & Connectivity / Knowledge library
EDNS — Extension Mechanisms for DNS
Extends DNS messaging using mechanisms such as the OPT pseudo-record.
Why learn EDNS — Extension Mechanisms for DNS?
Extends DNS messaging using mechanisms such as the OPT pseudo-record.
Where it came from
Larger UDP responses can still encounter fragmentation or path issues.
- Memory aid (a learning cue, not the expansion): Extend DNS without replacing the whole naming system.
Build your understanding
Work through these exercises in order. Try the task before opening a reference.
- Without looking, expand EDNS: Extension Mechanisms for DNS.
- Recall this memory aid: Extend DNS without replacing the whole naming system.
- Explain the practical use: Extends DNS messaging using mechanisms such as the OPT pseudo-record.
- Explain this distinction: Larger UDP responses can still encounter fragmentation or path issues.
- Identify EDNS in a device specification, architecture diagram, or system inventory.
Documentation and sources
- IETF RFC 6891 (www.rfc-editor.org)