What are the common DNS limitations for email records? (e.g., SPF lookups, TXT record length)
Key DNS limitations for email:
SPF lookup limit: Maximum 10 DNS lookups (include, a, mx, redirect, exists mechanisms). Exceeding causes permerror.
TXT string limit: 255 characters per string. Longer content must be split into multiple strings.
Total record size: Practical limits around 4096 characters for entire TXT record.
UDP response limit: Traditional 512 bytes. Larger responses may require TCP fallback.
Provider limits: Some providers restrict record count, length, or characters allowed.
These limits affect complex email setups. Plan authentication architecture to stay within limits.
Registry forms have size limits and section counts. Fit your documentation within the allowed structure.
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