For those of y’all unfamiliar with DNS, I recommend reading the rest of the series up till this point first before reading this one. Some of the concepts and terms I will be using here have been explained in those previous posts so I will not be explaining them again here.
Continue reading “Understanding DNS: Encrypted DNS”The Curious Case of basejumper.apple.com
After updating two of my iOS devices to iOS 17.1 I noticed some odd DNS queries coming from these devices in my local DNS resolver’s logs.
Oct 29 21:05:54 dnsmasq[1711]: query[A] basejumper.apple.com from 10.0.0.126
Oct 29 21:05:54 dnsmasq[1711]: cached basejumper.apple.com is NODATA-IPv4The odd thing here is that basejumper.apple.com does not resolve to anything. All A/AAAA/HTTPS queries for the name return a NOERROR empty response. So what is this endpoint?
Continue reading “The Curious Case of basejumper.apple.com”DNS TTL Limits at Public DNS Resolvers
In my post about the basics of DNS TTLs and caching I mentioned that DNS resolvers use the TTL of the record to determine how long to cache any particular record for. While this is /normally/ true, there are exceptions. Namely, certain public DNS resolvers have a upper limit of the TTL that they will cache. That is, if you set a TTL longer than their limit, the resolver will bring the TTL down to their limit and cache it using their TTL.
Continue reading “DNS TTL Limits at Public DNS Resolvers”Understanding DNS: TTLs and Caching
In my last post in this series I talked about common DNS record types, in this I am going to be talking about how the concept of TTLs (Time To Live) and caching are used in DNS.
The two concepts are interlinked in DNS, let’s get into it.
Continue reading “Understanding DNS: TTLs and Caching”Understanding DNS: Common Record Types
In my last post in this series I talked about authoritative nameservers and what they do. Their function is responding to queries for domain names they are authoritative for. These queries are for specific record types; in this post I will be talking about common record types you will encounter in your use of the DNS.
For the sake of simplicity and ease of understanding I’m limiting this post to the most common record types i.e records you are most likely to encounter and use in your day-to-day use of the DNS. These are not all the record types that are available for use in the DNS.
Let’s get started.
Continue reading “Understanding DNS: Common Record Types”