Blog categorized as Uncategorized

Interpreting ntpq output

06.10.2025 14:29:41 - By Paul Roberts - Comment(s)

Once again I had to google what a specific character meant (“o”) in the output from ntpq, here’s my output:

pi@ntp1:~ $ ntpq -pn
      remote           refid      st t when poll reach   delay   offset  jitter 
============================================================================== 
o127.127.22.0 ...

Impact of enabling querylogging on BIND

06.10.2025 14:17:07 - By Paul Roberts - Comment(s)

I recently had to undertake some DNS performance testing to ascertain the impact of enabling querylogging in BIND. The last time I did this must have been over 15 years ago and I was able to conclude back then that enabling querylogging had a substantial impact on the maximum throughput a DNS server...

Understanding ISC DHCP and “abandoned” leases

22.09.2025 15:48:33 - By Paul Roberts - Comment(s)

I have had several discussions lately relating to the recycling of abandoned leases in Infoblox DHCP (which is based upon ISC dhcpd). There seems to be a common misunderstanding about how the process works.

To recap, an abandoned lease occurs when the DHCP server encounters one of the following situa...

Using Infoblox DHCP failover

02.07.2024 10:41:28 - By Paul Roberts - Comment(s)

Infoblox DHCP is based upon ISC DHCP with a few tweaks here and there. The DHCP failover mechanism that it employs started as a relatively simple 14 page IETF draft proposal (available here) that was implemented in Alcatel-Lucent/Nokia VitalQIP (then Quadritek, the authors of the draf...