Setting A Single Search Domain With Dhcp Option 15; Setting Multiple Search Domains - Sennheiser MobileConnect User Documentation

Network integration

Setting a single Search Domain with DHCP Option 15

If you only need a single DNS search domain, simply set it via DHCP Option
15. This is standardized and well supported across all operating systems.
Again, if you use static IP Configuration for LAN2 on a ConnectStation,
make sure you manually set the "Search Domains" field there.

Setting multiple Search Domains

Most Operating Systems allow multiple search domains for their DNS loo-
kups which will be used one by one for DNS lookups. By standardization,
the DHCP Option 15 allows setting only a single domain, and there is a
further DHCP Option (119) to set multiple additional search domains.
Note: We found that Option 119 is not supported widely enough to be fun-
ctional for the purposes described here. Most notably, Android smartpho-
nes ignore the option completely in all versions we tested (4.1 to 6.0.1).
If you do need to set multiple search domains, we can suggest to add mul-
tiple search domains separated by space characters into DHCP Option
15. From our tests, this correctly works across iOS versions, it works for the
ConnectStation, and it "mostly works" for Android clients. Although our
tests have not been exhaustive, Windows-based clients seem to ignore any
domain after the first entry in this list.
On Android, our Apps (MobileConnect and CinemaConnect) correctly use
the full list of search domains passed via Option 15 to look up PTR and SRV
records. Discovery via hostname "sennheiser-connect" works only if the
hostname is configured with the first domain in the list.
Beware though that this use of Option 15 is outside the standard use of DH-
CP, yet seems a common practical solution to setting multiple search do-
mains. If you have services in your network that depend on the primary
domain setting from DHCP, make sure to test these after setting multiple
domains.
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