Challenge text suggested to lookup, took this to be a pointer for dns lookup, lucky guess
fire off dig to get all records we get a base64 string in the txt record
`dig any bitsctf.cf`
* ; <<>> DiG 9.11.5-P1-1-Debian <<>> any bitsctf.cf* ;; global options: +cmd* ;; Got answer:* ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35558* ;; flags: qr rd ra; QUERY: 1, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 1*  * ;; OPT PSEUDOSECTION:* ; EDNS: version: 0, flags:; udp: 512* ;; QUESTION SECTION:* ;bitsctf.cf.			IN	ANY*  * ;; ANSWER SECTION:* bitsctf.cf.		3599	IN	SOA	ns31.cloudns.net. support.cloudns.net. 2019020101 7200 1800 1209600 3600* bitsctf.cf.		3599	IN	A	35.226.250.134* bitsctf.cf.		3599	IN	NS	ns32.cloudns.net.* bitsctf.cf.		3599	IN	NS	ns33.cloudns.net.* bitsctf.cf.		3599	IN	NS	ns31.cloudns.net.* bitsctf.cf.		3599	IN	NS	ns34.cloudns.net.* bitsctf.cf.		3599	IN	TXT	"L25vZGUvZG5zLXRyb3VibGU="*  * ;; Query time: 100 msec* ;; SERVER: 8.8.8.8#53(8.8.8.8)* ;; WHEN: Tue Feb 05 12:34:36 CET 2019* ;; MSG SIZE  rcvd: 223
decoding using base64 -d we get/node/dns-trouble
Hitting the page, came up with nothing until checking the headers, the flag was in the X-Flag: response header
`BITSCTF{7h15_w45_345y_dn5}`