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In addition to the other comments which more directly address your question, DNS has been / can be used to exfiltrate data from “secure” networks. Search “dns data exfiltration” in your favourite search engine and you’ll get several high quality articles. Typical mitigations might be to limit which DNS servers your network can contact, restrict packet sizes to the bare minimum which valid use would have and so forth.
The one that’s stuck with me throughout a lifetime is The Hare and the Tortoise (Project Gutenberg, safe click). Slow but steady wins the race.