How to avoid fragmentation issues with DNS UDP query responses
Issue
- When a DNS (which will use UDP, by default) query response is bigger than 512 bytes, the packet will be truncated and retransmitted using TCP (which may be not desirable or even allowed)
- For small queries/replies, DNS uses UDP. When queries or replies get bigger than 512 bytes, then TCP is getting used.
Environment
- Red Hat Enterprise Linux (RHEL)
- Bind name server
- Identity Management (IdM) server, which has one component providing DNS services
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