Category: dns

Cache DNS server in SRX

Starting from 12.1X44-D10, an SRX box can also run as a cache only DNS server or dns proxy if we are to adhere to what is called in the documentation. It has also view support i.e you can direct DNS queries to specific DNS servers based on the source address.   In this topology, I
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DNS uses UDP or TCP?

As you know DNS uses UDP primarily as its transport layer protocol to communicate but for zone transfers (opcode AXFR,IXFR) it also uses TCP. There is one more indeed! DNS messages are restricted to 512 bytes and according to RFC 1035 (one of my favorites by the way), longer messages are truncated and TC bit
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Negative caching on DNS

Today I have increased the SOA minimum TTL value to increase my negative caching period but I have seen that no DNS server respect my change:) Here are two different results; From Google server [root@tux1 ~]# dig ; DiG 9.7.4b1-RedHat-9.7.4-0.3.b1.fc14 ;; global options: +cmd ;; Got answer: ;; ->>HEADERHEADER