Internet Protocols · Cluster
DNS
Resolution, delegation, and record semantics.
- 01 DNS Message Format and Name Compression on the Wire How the twelve-byte header, length-prefixed labels, and 0xC0 compression pointers carry a query and its answer, and which encodings a parser must reject.
- 02 Delegation and Zone Cuts: Where Authority Changes Hands How an NS RRset at a delegation point splits a namespace into zones, why glue records are necessary, and what makes a delegation lame or unreachable.
- 03 Iterative Resolution: Walking the Tree from Root Hints to Answer The referral chain a recursive resolver follows, how the cache shortens it, why the answer arrives as an RA response rather than a chain, and where the walk can stall.
- 04 Record Semantics: CNAME Exclusivity and RRset Atomicity Why a CNAME cannot coexist with other data at the same name, how RRsets are ordered and cached as units, and what an alias does to the query type.
- 05 Negative Caching: NXDOMAIN, NODATA, and the SOA Minimum How a resolver distinguishes a name that does not exist from a name with no records of the requested type, and how the SOA fields set the lifetime of both.
- 06 EDNS(0) and the Truncation Boundary How the OPT pseudo-record extends the header, how the advertised UDP payload size interacts with the 512-byte default, and why truncation is not a partial answer.
- 07 DNSSEC Validation and the Chain of Trust How DNSKEY, DS, and RRSIG records form a verifiable chain from the root to a leaf answer, and what a validator does when a link is missing or a signature has expired.
- 08 Zone Transfers and Secondary Replication: AXFR, IXFR, and the SOA Timers How a secondary server detects that a zone changed, what a full transfer costs against an incremental one, and how serial number arithmetic makes wrap-around safe.
- 09 Authenticated Denial of Existence with NSEC and NSEC3 How a signed zone proves that a name or type is absent, why NSEC leaks the zone inventory, and what hashing with NSEC3 costs in queries and opt-out coverage.
- 10 Encrypted DNS Transports and Their Trust Boundaries How DoT, DoH, and DoQ change the transport without changing the protocol, what each hides, and why the resolver becomes the party that sees every name.