linux

DNS Lookup

Uses curl to get a response from the specified domain. Useful for identifying the intermittent DNS timeout as well.

Abhith RajanSeptember 23, 2020 · 2 min read · Last Updated:
1for i in {1..10}; do curl -k -o /dev/null -s -w "DNS-Lookup [%{time_namelookup}] Time-Connect [%{time_connect}] Time-PreTransfer [%{time_pretransfer}] Time-StartTransfer [%{time_starttransfer}] Total-Time [%{time_total}] Response-Code [%{http_code}]\n" https://www.abhith.net; done

Sample Output

1root@pod-name-69d96c5494-bd97v:/app# for i in {1..10}; do curl -k -o /dev/null -s -w "DNS-Lookup [%{time_namelookup}] Time-Connect [%{time_connect}] Time-PreTransfer [%{time_pretransfer}] Time-StartTransfer [%{time_s
2tarttransfer}] Total-Time [%{time_total}] Response-Code [%{http_code}]\n" https://www.abhith.net; done
3DNS-Lookup [5.465393] Time-Connect [5.542967] Time-PreTransfer [5.626041] Time-StartTransfer [6.024135] Total-Time [6.261565] Response-Code [200]
4DNS-Lookup [0.458571] Time-Connect [0.536812] Time-PreTransfer [0.619370] Time-StartTransfer [0.960386] Total-Time [1.199219] Response-Code [200]
5DNS-Lookup [0.005218] Time-Connect [0.083305] Time-PreTransfer [0.167227] Time-StartTransfer [0.505865] Total-Time [0.745717] Response-Code [200]
6DNS-Lookup [5.066491] Time-Connect [5.144106] Time-PreTransfer [5.227078] Time-StartTransfer [5.585845] Total-Time [5.825170] Response-Code [200]
7DNS-Lookup [0.004125] Time-Connect [0.081587] Time-PreTransfer [0.165687] Time-StartTransfer [0.246201] Total-Time [0.481887] Response-Code [200]
8DNS-Lookup [0.005214] Time-Connect [0.083619] Time-PreTransfer [0.168375] Time-StartTransfer [0.510846] Total-Time [0.823167] Response-Code [200]
9DNS-Lookup [0.016983] Time-Connect [0.094932] Time-PreTransfer [0.177621] Time-StartTransfer [0.522677] Total-Time [0.758300] Response-Code [200]
10DNS-Lookup [0.005210] Time-Connect [0.083526] Time-PreTransfer [0.166203] Time-StartTransfer [0.246943] Total-Time [0.481547] Response-Code [200]
11DNS-Lookup [0.010488] Time-Connect [0.088643] Time-PreTransfer [0.172099] Time-StartTransfer [0.517206] Total-Time [0.829188] Response-Code [200]
12DNS-Lookup [0.005282] Time-Connect [0.083156] Time-PreTransfer [0.167259] Time-StartTransfer [0.499211] Total-Time [0.734148] Response-Code [200]
13root@pod-name-69d96c5494-bd97v:/app#

Noticed the 5sec+ responses above? Explore more about the intermittent delay in Kubernetes in these articles,

Written by Abhith Rajan
Abhith Rajan is an aspiring software engineer with more than 8 years of experience and proven successful track record of delivering technology-based products and services.
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