Tag

dns

17 articles

Sep 14, 2026 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. internet protocols
Jun 15, 2026 SPF Evaluation and Its Ten-Lookup Budget How a receiver matches a sending IP against a domain policy written in TXT records, why the recursion limit exists, and what each result value actually permits. internet protocols
Feb 4, 2026 What a Connectivity Callback Reports and What It Cannot Why the operating system reports a network as available before it can reach anything, and which checks distinguish a captive portal from an outage from a broken name lookup. mobile computing
Nov 18, 2025 Counting Round Trips in Connection Setup How handshakes, name resolution, and security negotiation add serial round trips before the first byte of payload, and which of them can be overlapped. networking
Oct 17, 2025 DNS TTL, Resolver Caches, and the Real Duration of a Cutover How negative caching, recursive resolvers, and connection reuse stretch a five-minute TTL into hours of split traffic, and what actually bounds the redirect window. cloud infrastructure
Oct 9, 2025 Detecting DNS Tunnels from Query Structure How DNS becomes a bidirectional data channel, which structural properties of queries carry the signal, and why entropy alone is a weak discriminator against legitimate naming schemes. security
Aug 22, 2025 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. internet protocols
Apr 18, 2025 DNS Failover and the Resolver Caching Bound How record TTLs, negative caching, and resolver behaviour put a floor under DNS-based traffic redirection, and why the observed switchover time exceeds the TTL. cloud infrastructure
Mar 27, 2025 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. internet protocols
Jan 21, 2025 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. internet protocols
Jan 18, 2025 MX Resolution, Preference Ordering, and Null MX How a sending server turns a domain into a list of hosts, why the preference values are ordered the way they are, and what an empty MX list asserts. internet protocols
Dec 15, 2024 Private Endpoint Services and the Reverse-Direction Connection How a service in one VPC becomes reachable from another through an address that lives in the consumer subnet, why the connection is accepted by the provider, and what the endpoint does not hide. cloud infrastructure
Aug 23, 2024 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. internet protocols
Mar 5, 2024 DNS Delegation, Glue Records, and the Referral Loop How authority for a name is handed down a zone tree, why a child in the same zone as its parent forces address records into the parent, and what breaks when glue is wrong. computing history
Oct 12, 2022 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. internet protocols
Oct 10, 2022 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. internet protocols
Nov 11, 2021 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. internet protocols