Read a referral without confusing it with an answer
01A parent points the resolver to child name servers and supplies addresses needed to reach them.
Using 192.0.2.1, the resolver can send its DNS question to a foo.test child server. This is the next lookup step, not a completed website answer.
Source for this drawing: RFC 9471 · Read RFC section 2.1 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DNS means Domain Name System. An iterative resolver follows referrals itself. A delegation gives another zone responsibility for part of the name tree; an NS record names one of that zone’s name servers (§§1–2.1).
- DNS means Domain Name System. An iterative resolver follows referrals itself. A delegation gives another zone responsibility for part of the name tree; an NS (name server) record names one of that zone’s name servers (§§1–2.1).
- For the question A www.foo.test., the test parent can refer the resolver to foo.test. The authority section carries foo.test. NS ns1.foo.test. and NS ns2.foo.test.; these are server names, not addresses or an answer for www.foo.test. (§2.1; RFC 1034 §4.3.2 step 3(b)).
- The additional section supplies available IPv4 (A) and IPv6 (AAAA) address glue for those name-server names. In the RFC example, ns1.foo.test. has A 192.0.2.1 and ns2.foo.test. has AAAA 2001:db8::2:2. An A question for the website does not limit glue to A: these records describe different names (§§2.1,3.1).
- Without an initial address for a server inside the delegated zone, the resolver can need to contact that same zone to learn how to contact it. Glue in the parent breaks this bootstrap dependency. The final picture reaches a child server; it does not invent an answer for the original website (§1).
Fictional DNS examples use documentation names and addresses. Record blocks and remaining budgets are schematic supplied costs, not a DNS wire encoder or a complete resolver.
Read the RFC section ↗