pjhtech ToolsRecord types
| Type | Purpose | Common mistake |
|---|---|---|
| A | Name to IPv4 address | Putting a URL or port in address data |
| AAAA | Name to IPv6 address | Publishing an address without working IPv6 connectivity |
| CNAME | Alias to another DNS name | Combining with other ordinary data at the same owner |
| MX | Mail exchanger with preference | Using an IP instead of a hostname |
| TXT | Text strings, including verification data | Publishing conflicting SPF records |
| NS | Authoritative name servers | Confusing a registrar setting with zone data |
| SOA | Zone authority and timing metadata | Ignoring serial updates in manually managed zones |
| PTR | Reverse address name to hostname | Assuming an A record creates reverse DNS |
| SRV | Service target, port, priority and weight | Using it for clients that do not support SRV |
| CAA | Certificate-authority authorization | Treating it as a certificate or ownership proof |
| Type | Purpose | Watch for |
|---|---|---|
| HTTPS / SVCB | Service endpoint and connection parameters | Client support and AliasMode vs ServiceMode |
| DS / DNSKEY | DNSSEC chain of trust / public zone keys | Coordinate a rollover with the parent |
| RRSIG | Signature over a record set | Validity dates differ from cache TTL |
Forward and reverse example
A documentation host named router.lab.invalid could have A data 192.0.2.42 and AAAA data 2001:db8:42::1. Its IPv4 PTR owner would be 42.2.0.192.in-addr.arpa. The .invalid name is intentionally nonresolving; these are teaching values, not deployment records.
TTL and changes
TTL is a cache lifetime in seconds, not a promise that every client refreshes instantly. Lowering a TTL does not evict an older cached answer. Plan ahead and account for negative caching when introducing names.
Names and delegation
A trailing dot represents an absolute DNS name in zone-file notation. Provider interfaces may add the zone name automatically, so inspect their instructions before entering a fully qualified value. Reverse DNS is controlled by the address-space operator and can require a separate request.
Alias caution
A conventional CNAME cannot coexist with other ordinary records at the same owner name. At a zone apex, required SOA and NS data make a normal CNAME unsuitable. Provider-specific alias or flattening products are distinct features.